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The Indian Society of Forage Research

(Regd. No. 41/1974-75)

The Society was founded in October 1974 with the following objectives :

1. To advance the cause of research activity in all aspects of forages in India and to encourage and promote study and research on these crops.
2. To disseminate the knowledge of scientific agriculture and technology in the production of forages.
3. To provide facilities for association and conference among forage research scientists and for the encouragement of close relationship between the scientists, cultivators, industrialists and traders of feeds and fodders.

EXECUTIVE COUNCIL (2019-20)

Patron : Dr. T. C. Mahapatra Secretary : Dr. R. S. Sheoran President : Dr. I. S. Solanki Treasurer : Dr. Bhagat Singh Vice-Presidents : Dr. Vilas A. Tonapi Joint Treasurer : Mr. Satpal : Dr. R. K. Yadava Editor : Dr. S. K. Pahuja

COUNCILLORS

Dr. R. N. Arora (Hisar) Dr. Hans Raj Mehla (Jodhpur) Dr. S. S. Sehkawat (Bikaner) Dr. K. S. Dangi (Hyderabad) Dr. Umakant (Hyderabad) Dr. Naveen Kumar (Palampur) Dr. Yogesh Jindal (Hisar) Dr. A. K. Roy (Jhansi) Dr. N. K. Thakral (Hisar) Dr. A. Henry (Jodhpur)

EDITORIAL BOARD

Dr. S. Ravi Kumar (Hyderabad) Dr. D. S. Phogat (Hisar) Dr. Rajesh Yadav (Hisar) Dr. Joseph (Imphal) Dr. Ashok Yadav (Palampur) Dr. Ram Avtar (Hisar) Dr. Parem Singh Yadav (Hisar) Dr. J. K. Bisht (Almora) Dr. D. K. Banial (Palampur) Dr. A. K. Dhaka (Hisar) Dr. Pummy Kumari (Hisar) Dr. M. K. Singh (Hisar) Dr. Suresh Kumar (Hisar) Dr. Satywan Arya (Hisar) Mr. Ravish Panchta (Hisar) Dr. Jayanti Tokas (Hisar) Dr. Dalvinder Pal Singh (Hisar) Dr. Maninder Kaur (Ludhiana) Dr. R. A. Gami (Gujarat)

CONSULTING EDITORS OVERSEA

Dr. Rakesh Godara (USA) Dr. Nguyen Ngoc Vu (Vetnam) Dr. Virander Kumar (Philippines) Dr. Krishna Kumar Sugumaran (Kuwait) Dr. Cleto Namoobe (Zambia) Dr. Bahy R. Bakheit (Egypt)

ADVISORY BOARD

Dr. H. P. Yadav (India) Dr. Arun Sharma (USA) Dr. Sudhir Yadav (Philippines) Dr. M. K. I. Khan (Bangladesh) Dr. U. N. Joshi (India) Dr. U. S. Tiwana (India) Editorial Secretary : Dr. Rajesh Arya

FORAGE RESEARCH

(Regd. No. 26388/75) Edited by Dr. S. K. PAHUJA

FORAGE RESEARCH, which is the official journal of the Indian Society of Forage Research, is published four times in year (March, June, September & December). The subscription rates are as under :

For institutions in India Rs. 1500.00 per year Other countries US $ 85.00 per year Annual membership for individuals Rs. 500.00 per year Life membership Rs. 5000. All correspondence regarding publication should be addressed to The Editor, Forage Research, CCS Haryana Agricultural University, Hisar-125 004. The communication regarding business matters should be addressed to Dr. Bhagat Singh, Treasurer, Indian Society of Forage Research, CCS Haryana Agricultural University, Hisar-125 004 (Haryana), India.

BREEDING FORAGE CROPS FOR IMPROVED ABIOTIC STRESS TOLERANCE-A REVIEW

J. S. VERMA* Department of Genetics and Plant Breeding G. B. Pant University of Agriculture & Technology, Pantnagar-263 145, India *(e-mail : jsverma21@yahoo.in) (Received: 25 February 2019; Accepted: 3 May 2019)

SUMMARY

Forage crop production is largely limited by abiotic stress such as drought, salinity, temperature and other edaphic stresses because most forages are grown in marginal agricultural lands that have even poorer soil and land management system featured with low water holding capacity, infrequent irrigation, limited fertility or high salt content. Conventional and genetic engineering approaches have been used to improve stress tolerance of forage grasses and legumes. Modern conventional plant breeding is undergoing revolutionary changes that embrace new marker technologies and more profound understanding of the mechanisms that constitute complex traits. Traditionally, major gene and polygenic variation has been analyzed in different ways, but the use of new DNA markers and techniques of QTL analysis now allow to more integrated approaches in dissecting complex traits and assessing gene effects. Useful information on the genetic basis of abiotic stress tolerance has been obtained by moving genes between plants of the same or closely related species. Gene introgression achieved by conventional cross pollination means that created a range of genetic variation available to understand and manipulate genetic adaptation to environmental change is greatly enhanced. Drought and cold tolerance has been improved within the Lolium / Festuca species complex. A link was found between drought tolerance and enhanced deeper root growth under water limiting conditions in tall fescue and alfalfa. The differences in the level of freezing tolerance between non-hardy and hardy alfalfa cultivars was found to be related to the capacity of the plants to accumulate raffinose and stachyose in their roots and crowns other than the capacity to accumulate sucrose earlier than non-dormant plants. Proline content in alfalfa leaves and roots increased dramatically when plants were subjected to drought and two genes controlling the transcriptional regulation of key proline cycle enzymes in alfalfa have been identified and cloned. Wide hybridization with relative species followed by chromosome and / or chromosome fragment introgression has been considered an efficient way to transfer drought, salt and other stress tolerance gene(s) to the target species to widen the gene pool. Intergeneric hybrids between Lolium (Ryegrass) and Festuca (Fescue) species have received much attention by forage breeders. Enhanced drought tolerance in cowpea is accompanied with (i) better water- use efficiency and tolerance to water –deficiency and extreme heat conditions, (ii) better recovery of plants after drought is removed i.e., on re-watering. Both types of drought tolerance are dominant traits controlled by a single dominant gene Rds1 and Rds2 respectively. In white clover drought tolerance improvement programme, introgression has also been used as a route to transfer the morphological or physiological traits from its related wild species that show more drought tolerance or have better persistence. Endophyte- infected grasses are better adapted than non-infected grasses to abiotic stresses i.e., drought and marginal soil conditions due to direct changes affecting water status in shoots and indirect changes in root morphology and function.

Key words : Abiotic stress, tolerance, forage crops, breeding, intergeneric hybridization, endophyte

Forage Res., 45 (1) : pp. 1-9 (2019) http://forageresearch.in

In agricultural context, stress has been defined as the conditions in which plants are prevented from fully expressing their genetic potential for growth, development, reproduction and ultimately the crop productivity (Levitt, 1980). Abiotic stresses adversely affect the livelihoods of farmers and their families, sustainability of livestock as well as national economies and food security. Forages are normally

referred to as plants and plant parts that are consumed by domestic livestock such as dairy and beef cattle, sheep, goats, horses and a wide range of other animals (Barnes and Baylor, 1995). Forage plays a key role in ruminant livestock production and environment protection. In addition to serving as the major sources of feed nutrients for domestic and wild animals, forages contribute to human well-being through many

genes on chromosome 2 for drought resistance derived from Festuca arundinacea (Humphreys and Pasakinskiene, 1996).

Genetics of Abiotic Stress Tolerance

Successful breeding depends on a broad understanding of the genetic architecture of relevant traits. Genes with major effects and genes contributing to the expression of quantitative traits both have a role in controlling abiotic stress tolerance. Traditionally, major gene and polygenic variation has been analyzed in different ways, but the use of new DNA markers and techniques of OTL analysis now allow to more integrated approaches in dissecting complex traits and assessing gene effects. Genetic fingerprinting of Hordeum spontareum has revealed genetic marker associations with eco-geographic factors and experimentally imposed stresses (Forster et al ., 2000). Examples of QTL associated with valuable traits are increasing in wide range of crops including rice, wheat, maize, sorghum, barley, forage and turf grasses. Useful information on the genetic basis of abiotic stress tolerance has been obtained by moving genes between plants of the same or closely related species. Gene introgression achieved by conventional cross pollination means that created a range of genetic variation available to understand and manipulate genetic adaptation to environmental change is greatly enhanced. In barley, greater variation to abiotic stress exists in primitive landraces and gene pools in related wild species (Forster et al ., 2000), which are easily hybridized with cultivated barley to provide extended sources of variation. Drought and cold tolerance has been improved in hybridization within the Lolium / Festuca species complex (Humphreys et al ., 1998). White clover plants have been produced with varying resource allocation in stolons and rhizomes, which also affects tolerance to stresses such as cold and drought (Marshall et al ., 2001). Advances in understanding the effectiveness of stress responses are also being made using transgenic plant analysis (Hasegawa et al ., 2000). However, it is also true that drought/salinity tolerant transgenic crop plants are yet away from the reach of farmers.

Stress Responses and Physiology

Tall fescue ( F. arundinacea ) 2n=6x=42, a cool season perennial grass species is the most important forage species. Tall fescue is better adapted to avoid drought than other cool-season grasses such as other perennial ryegrasses partially due to bigger

root size (length or mass) and spatial distribution. A link was found between drought tolerance of tall fescue and enhanced deeper root growth under water limiting conditions (Huang and Fry, 1998; Huang and Gao, 2000). This findings has been used in drought tolerance breeding programmes by selecting low shoot-to-root ratios in turf type tall fescue populations (Bonos et al ., 2004). Obligatory summer dormancy (defined as plant dormancy in response to increased day length and probably high temperature) has been found in some cool-season perennial grasses (Ofir and Kigel, 1999). Obligatory summer-dormant tall fescue had better drought tolerance (Malinowski, et al ., 2005). The mechanism of obligatory summer-dormancy remained to be understood at the physiological, biochemical and molecular levels. Alfalfa ( Medicago sativa L., 2n=4x=32) is grown extensively throughout temperate and tropical regions for green fodder, hay, silage and pasture. Alfalfa combines high biomass productivity, optimal nutritional profiles and adequate persistence, thus making it ideal for dairy cattle and other livestock (Brummer, 2004). As a perennial forage crop, alfalfa is a fairly hardy species and has a relatively high level of drought tolerance compared with many other legume forages (Barnes and Sheaffer, 1995). The greater drought tolerance of alfalfa is partially due to deeper roots and the ability to extract more available water in the root zone (Hall, 2001). Alfalfa becomes dormant during periods of cold or severe drought and may last for 1 to 2 years until the temperature or moisture available to resume growth (Barnes and Sheaffer, 1995). Screening for salt responsive proteins in two contrasting alfalfa cultivars using a comparative proteome approach revealed two novel proteins NAD synthetase and biotin carboxylase-3, as salt-responsive. These results provide new insight of salt stress tolerance in alfalfa (Rahman et a l., 2015). Effects of rhizobial strains on the amino acid composition in alfalfa under salt stress indicated that proline, glutamine, arginine, GABA and histidine substantially accumulated in salt stresses nodules, suggesting an enhanced production of amino acid associated with osmoregulation, N storage or energy metabolism to counteract salt stress (Bernard et al., 2016). The mechanism controlling winter hardiness in alfalfa (Lucerne) have been investigated with biochemical and molecular approaches. The differences in the level of freezing tolerance between non-hardy and hardy alfalfa cultivars was found to be related to the capacity of the plants to accumulate raffinose and stachyose in their roots and crowns other

FORAGE BREEDING FOR ABIOTIC STRESS 3

than the capacity to accumulate sucrose (Castonguay et al ., 1995) earlier than non-dormant plants. During drought or salt stress, plants induce processes that regulate osmotic adjustment to maintain sufficient cell turgor partially through accumulation of compatible solutes comprised of mainly nontoxic low molecule chemicals viz., sucrose, fructose sugar alcohols, proline and glutamic acid in shoots and roots. Accumulation of proline upon dehydration due to water deficit, high salinity and low temperature has been reported in bacteria, algae and higher plants and the causal relationship between increased proline accumulation and plant tolerance of hyper-osmotic stresses has been demonstrated (Hare et al ., 1999). Proline content in alfalfa leaves and roots increased dramatically when plants were subjected to drought (Goicoechea, et al ., 1998). Two genes controlling the transcriptional regulation of key proline cycle enzymes in alfalfa have been identified and cloned (Miller et al ., 2005). White clover ( Trifolium repens L. 2n=4x=32) is an allotetraploid forage legume species widely distributed in the world due to its wide range of climatic adaptation (Pederson, 1995). But it is less tolerant to drought compared with other perennial temperate forage legumes because of its shallow root system and inability to effectively control transpiration (Annicchiarico and Piano, 2004). The major feature of white clover is its soloniferous habit. It spreads by growth of stolons with adventitious roots developing at the nodes. The persistence, under water stress, is largely dependent on the ability of vegetative stolons to survive variable periods of drought (Williams, 1987). So the development of a strong network of stolons is a prerequisite and stolon characters have a major focus of breeding efforts in this species (Sanderson et al ., 2003). Biochemical studies indicated that when white clover was stressed with water deficit, the de novo amino acid synthesis including proline was increased in both leaves and roots (Lee et al ., 2005). The phenomenon may serve as adaptive response during first few days in drought stress, as the transient increase of amino acid concentration was followed by decrease of protein synthesis that make the plants grow slower.

Cowpea ( Vigna unguiculata L. Walp.) which is grown in varied environments from tropical to arid/ semi-arid regions, enhanced drought and heat tolerance would be desirable. Enhanced drought tolerance in cowpea is accompanied with (i) better water- use efficiency and tolerance to water –deficiency and extreme heat conditions, (ii) better recovery of plants

after drought is removed i.e., on re-watering. Two types of drought tolerance mechanisms observed. Type 1 : Lines stopped growth, conserved moisture in all the plant tissues and stayed alive for over two weeks and gradually entire plant dried together. Type 2 : Lines continued slow growth, mobilizes moisture from lower leaves to growing tips and remain live for longer time while lower leaves die one by one. Better regeneration after re-watering. Both types of drought tolerance are dominant traits controlled by a single dominant gene Rds1 and Rds2 respectively. Test of allelism indicated that Type 1 is dominant over type 2 (when together) and the F (^2) population between two types segregated in the ratio 3:1 (Type1:Type 2) plants. Breeding efforts to combine deep root systems with drought tolerance to enhance plants ability to absorb moisture from receding water after the rains ceases. Several drought tolerant lines have been identified viz., TVu 11986, TVu 11979, IT93K – 451-1 (Type 1), while Dan Ila, IT89KD – 288 – 40, IT97K – 1025 – 18, IT 99K – 687, IT 99 K

• 695 (Type 2) (Singh and Matusi, 2002). The beach cowpea ( Vigna marina ssp. oblonga ) growing on sandy beaches in subtropical and tropical regions closest of the sea has potential to be a gene source for breeding salt tolerant cultivars. Chankaew et. al ., (2014) for the first time reported the mapping of QTL for salt tolerance in Vigna marina , and multiple internal mapping consistently identified one major QTL which can explain 50% of phenotypic variance. The flanking marker may facilitate transfer of salt tolerance from this sub species into related Vigna crops.

Improvement of Stress Tolerance by Intergeneric Hybridization

Wide hybridization with relative species followed by chromosome and/or chromosome fragment introgression has been considered an efficient way to transfer, salt and other stress tolerance gene(s) to the target species to widen the gene pool. Intergeneric hybrids between Lolium (Ryegrass) and Festuca (Fescue) species have received much attention by forage breeders. Ryegrasses are considered the ideal grasses due to their rapid establishment, ability to withstand heavy grazing, good palatability and high nutritious value (Humphreys et al ., 2003). However, their growth is restricted only to some European countries, some regions in Australia, New Zeeland and Southeast US because they are not sufficiently robust to meet many of the environmental challenges in less

4 VERMA

Medicago truncantula is an omni- mediterranean forage legume species and is closely related to world’s most important forage legume alfalfa, Medicago sativa (May, 2004). Two genes designated as WXP 1 and WXP 2 cloned from Medicago truncantula are novel transcription factor genes, which activate wax production in the acyl-reduction pathway. Over expression of WXP 1 and WXP 2 under the control of the CaMV35S promoter led to significant increase in cuticular wax loading on leaves of transgenic alfalfa. The increase in wax production was mainly contributed by the increase in C-30 primary alcohol. The electron microscopy scanning revealed that the density of wax crystalline structures on both adaxial and abaxial surfaces of mature leaves was higher in transgenic than in control plants. Transgenic leaves showed reduced water loss and chlorophyll leaching. Transgenic alfalfa plants with increased cuticular waxes showed enhanced drought tolerance demonstrated by delayed wilting after watering was ceased and quicker and better recovery when the dehydrated plants were re-watered (Zhang et al ., 2005). A common problem in irrigated agriculture is the gradual buildup of salts in the root zone; which can be detrimental to sustained crop production. Salt stress significantly limits productivity of alfalfa via its adverse effect on growth and symbiotic nitrogen- fixation capacity. Recent progress has been made in the identification and characterization of the mechanisms that allow plants to tolerate high salt concentration. Identification of different sodium transporters e.g ., plasma membrane Na+/H+^ antiporters allows the engineering of crop plants with improved salt tolerance (Apse and Blumwald, 2002). The antiporters are prevalent membrane proteins present in Bacteria, yeasts, animals and plants. The vacuolar Na +^ /H +^ antiporter catalyzes the exchange of Na+^ and H +^ across the plasma membrane contributing to the regulation of internal pH, cell volume and sodium concentration. The vacuolar Na +^ /H +^ antiporter can pump Na +^ from cytoplasm into vacuole, to maintain a higher K +^ /Na +^ ratio in cytoplasm than in vacuoles, protecting cell from sodium toxicity. Recently a vacuolar Na+^ /H +^ antiporter gene cloned from rice was over expressed in perennial ryegrass by agro bacterium mediated transformation. The transgenic ryegrass plants had dramatically improved salt tolerance under 100-350 m mol/L Nacl treatment. The leaves of transgenic plants accumulated higher concentration of Na +, K +^ and proline than those of the control plants (Wu, et al ., 2005). Transcription

factors (TF) play classical roles in regulating various abiotic stress responses. The current developments in understanding TFs, with particular emphasis on their function in orchestrating plant abiotic stress responses have been discussed (Chen et al ., 2018 and Khan et al., 2018).

Drought Tolerance via Symbiosos with Endophyte

Tall fescue ( Festuca arundinacea ) plants, the most widely planted forage grass, are commonly symbiotically infected with the endophytic fungus Neotyphodium coenophialum (Bouton and Easton, 2005). The relationship between the endophytic fungus and plant is generally considered mutualistic because endophyte significantly improves host plant tolerance to drought along with increased persistence and vigour and in turn plant provides the symbiont with nutrients, protection and reliable and efficient dissemination (Schardl et al ., 2004). Endophyte-infected grasses are better adapted than non-infected grasses to abiotic stresses i.e., drought and marginal soil conditions due to direct changes affecting water status in shoots and indirect changes in root morphology and function (Malinowski and Belesky, 2000). These adaptations may arise from a chemical signaling system in the symbiotum. Apparently, drought signals sensed by roots can be received by endophyte and induce a range of responses in host plants. Less is known about the chemistry of these signals. The possible mechanism of drought tolerance includes improved water uptake from the soil as of extensive root system - decreased root diameter and increased root hair length (Malinowski and Belesky, 2000), better control of transpiration by rapid stomata closure (Elmi and West, 1995), better water storage in tiller base by reduced leaf conductance (Elbersen and West, 1996) and enhanced drought tolerance by inducing rapid accumulation of compatible solutes like glucose, fructose, sugar alcohols proline and glutamic acid in shoots and roots. The fungal metabolites like mannitol and loline alkaloids also significantly increased with the water deficit (Bush et al ., 1997 and Nagabhyru et al ., 2013). Animals feeding on endophyte infected (E+^ ) tall fescue cultivars suffer from fescue toxicosis which causes poor weight gain and reproduction problems (Sleper and West, 1996). Ergot alkaloids, especially ergovaline derived from the endophyte association are considered to be responsible for most animal problems (Lyons et al ., 1986). However, introducing endophyte- free tall fescue varieties has not been very successful

6 VERMA

because of their poor persistence once exposed to abiotic stresses. A very useful approach is to isolate naturally occuring, non-ergot-producing strains and re- infecting elite varieties. One such novel endophyte strain AR542 has been selected in New Zealand, which was used to re-infect tall fescue varieties Jsup and Georgia 5 in the United States (Bouton et al ., 2002). More novel endophyte isolations have been characterized and are being used for re-infection of tall fescue and perennial ryegrass cultivars and breeding lines. Another promising approach to deal with this problem is genetic manipulation of Neotyphodium spp. endophyte to eliminate the toxin from the symbiosis (Panaccione et al ., 2001).

REFERENCES

Abberton, M. T. and A. H. Marshall, 2005 : Progress in breeding perennial clovers for temperate agriculture. Journal of Agriculture Science , 143 : 117-135. Abberton, M. T., T. P. T. Yeates Michaelson, A. H. Marshall, K. Smith Holdbrook and I. Rhodes, 1998 : Morphological characteristics of hybrids between white clover, Trifolium repens L. and Caucasian clover, Trifolium ambiguum M. Bieb. Plant Breeding , 117 : 494-496. Aleliunas, A., K. Jonaviciene, G. Statkeviciute, D. Vatiekunaite, V. Kemesyte, T. Lubberstedt and G. Brazaukas, 2015 : Association of single nucleotide polymorphisms in lp IRI1 gene with freezing tolerance traitsin Perennial ryegrass. Euphytica, 204(3): 523-534. https://doi.org/10.1007/s10681- 014-1330-y Annicchiarico, P. and E. Piano, 2004 : Indirect selection for root development of white clover and implications for drought tolerance. Journal of Agronomy and Crop Science , 190 : 28-34. Apse, M. P. and E. Blumwald, 2002 : Engineering salt tolerance in plants. Current Opinion of Biotechnology , 13 : 146-150. Barnes, D. K. and C. C. Sheaffer, 1995 : Alfalfa. In : Forages : An Introduction to Grassland Agriculture, R. F. Barnes,; D. A. Miller, C. J. Nelson, (eds.). Iowa State University Press, Ames, Iowa, pp. 205-216. Barnes, R. F. and J. E. Baylor, 1995 : Forages in a changing world. In : Forages : An Introduction to Grassland Agriculture, R. F. Barnes, D. A. Miller, C. J. Nelson, (eds.). Iowa State University Press, Ames, pp. 3-13. Bernard, A., M, Bipfubusa, C, Dhont, F. P, Chalifour, P, Drouin and C. J. Beauchamp. 2016 : Rhizobial strains exert a major effect on the amino acid composition of alfalfa nodules under Nacl stress. Plant Physiol. Biochem ., 108 : 344-352. Bonos, S. A.., D. Rush, K. Hignight, and W. A. Meyer, 2004: Selection for deep root production in tall fescue

and perennial ryegrass. Crop Science , 44 : 1770-

Bouton, J. and S. Easton, 2005 : Endophytes in forage cultivars. In : Neotyphodium in Cool-season Greasses. C. A.. Roberts, C. P. West, D. E. Spiers, (eds.). Blackwell Publishing, Ames, IW. Bouton, J. H., G. C. M Latch, N. S. Hill, C. S. Hoveland, M. A McCann, R. H. Watson, J. A. Parish, L. L. Hawkins, and F. N. Thompson, 2002 : Reinfection of tall fescue cultivars with non-ergot alkaloid producing endophyte. Agronomy Journal , 94 : 567-574. Breshears, D. D., N. S. Cobb, P. M. Rich, K. P. Price, C. D. Allen, R. G. Balice, W. H. Romme, J. H. Kastens, M. L. Floyd, J. Belnap, J. J. Anderson, O. B. Myers and C. W. Meyer, 2005 : Regional vegetation die- off in response to global-change-type drought. PNAS , 102 : 15144-15148. Brummer, E. C. 2004 : Applying genomics to alfalfa breeding programme. Crop Science , 44 : 1904-

Bush, L. P., H. H. Wilkinson, and C. L. Schardl, 1997 : Bioprotective alkaloids of grass-fungal endophyte symbioses. Plant Physiology , 114 : 1-7. Canter, P. H., I. Pasakinskiene, R. N. Jones, and M. W. Humphreys, 1999 : Chromosome substitutions and recombination in the amphiploid Lolium perenne

- Festuca pratensis cv Prior (2n=4x=28). Theor. Appl. Genet. 98 : 809-814. Casler, M. D., P. G. Pitts, F. C. Rose, P. C. Bilkey and J. K. Wipff, 2001 : Registration of “Spring Green” festulolium. Crop Sci. 41 : 1365-1366. Castonguay, Y., P. Nadeau, P. Lechasseur, and L. Chouinard, 1995 : Differential accumulation of carbohydrates in alfalfa cultivars of contrasting winterhardiness. Crop Science , 35 : 509-516. Chankaew, S., T, Semura, K. Naito, O.E. Tanaka, N. Tomorka, P. Somta, A. Kaga, D.A. Vaughan and Srinives, 2014 : QTL mappingfor salt tolerance and domestication related traits in Vigna marina ssp. oblonga. Theor. Appl. Genet ., 127(3) ; 691-

Che, D., S. Chai, C.L. Mcintyre and G.P. Xue. 2018. Over expression of a predominantly root-expressed NAC transcription factor in wheat roots enhances root length, biomass and drought tolerance. Plant Cell Rep ., 37 : 225-237. Dabkeviciene, G, V. Kemesyte, G. Statkeviciute, N. Lemeziene and G. Brazaukas. 2017. Autotetraploids in fodder grass breeding: induction and field performance. Spanish J. Agril. Res., 15(4), e 0706, 7 pages. https: /doi.org/ 10.5424/sjar/2017154-11357. Eagles, C. F., H. Thomas, F. Volaire, and C. J. Howwarth, 1997 : Stress physiology and crop improvement. In : Proc. XVIII Intl. Grassland Cong., B. R. Christie, (ed.). Canada. Elbersen, H. W. and C. P. West, 1996 : Growth and water relations of field-grown tall fescue as influenced

FORAGE BREEDING FOR ABIOTIC STRESS 7

physiological traits. Ekin J. 2 : 74-81. Nagabhyru, P., R. D. Dinkins, C. L. Wood, C. W. Bacon, and C. L. Schardl, 2013 : Tall fescue endophyte effects on tolerance to water-deficit stress. BMC Plant Biology , 13 : 127. Ofir, M. and J. Kigel, 1999 : Photothermal control of the imposition of summer dormancy in Poabulbosa, a perennial grass genophyte. Physiology Planta. 105 : 633-640. Panaccione, D. G., R. D. Johnson, J. Wang, C. A. Young, P. Damrongkool, B. Scott, and C. L. Schardl, 2001 : Elimination of ergovaline from a grass- Neotyphodium endophyte symbiosis by genetic modification of the endophyte. PNAS , 98 : 12820-

Pederson, G. A. 1995 : White clover and other perennial clovers. In : Forages. I. An Introduction to Grassland Agriculture, R. F. Barnes,; D. A. Miller, C. J. Nelson, (eds.). Iowa State University Press, Ames, Iowa, pp 205-216. Pereira, R.C., MTM Manzanera, L.C. David, M. Pasqual, A. Mittleman and V. H. Techio,. 2014 : Chromosome duplication in Lolium multiflorum Lam. Crop Breed. Appl. Biotech. 14(4) : 251-255, https://doi.org/10-1590/1984-70332014v1590. Rahman, M.A., I, Alam, Y.G. Kim,N.Y.Ahn, S.H. Heo, P.G. Lee, G. Lu and B.H. Lee, 2015 : Screenig for salt responsive proteins in two contrasting alfalfa cultivars using a comparative proteome approach. Plant Physiol. Biochem ., 89 : 112-122. Richards, R. A. 1996 : Defining selection criteria to improve yield under drought. Plant Growth Regulation , 20 : 157-166. Sanderson, M. A., R. A. Byers, R. H. Skinner and G. F. Elwinger, 2003 : Growth and complexity of white clover stolons in response to biotic and Abiotic stress. Crop Science , 43 : 2197-2205. Sanderson, M. A., D. W. Stair, and M. A. Hussey, 1997 : Physiological and morphological response of perennial forages to stress. Advances in Agron ., 59 : 171-224. Schardl, C. L., A. Leuchatmann and M. J. Spiering, 2004 : Symbioses of grasses with Seedborne fungal endophytes. Annual Review of Plant Biology , 55 : 315-340. Singh, B.B. and T. Matusi, 2002 : Cowpea varieties for drought tolerance. In : Challenges and Opportunities for Enhancing Sustainable Cowpea Production, C.A. Fatokun, S. A. Tarawali, B. B. Singh, P. M. Kormawa and M. Tamo (eds.). IITA, Ibadan, Nigeria pp. 287-300.

Sleper, D. A. and C. P. West, 1996 : Tall fescue. In : Cool- season Forage Grasses. L. E. Moser, D. R. Buxton, and M. D. Casler, (eds.) American Society of Agronomy, Crop Science Society of America, Soil Science Society of America, Madison, WI, pp 471-

Swarnendu Roy and Chakraorty, Usha. 2014. Salt tolerance mechanisms in salt tolerant grasses (STGs) and their prospects in cereal crops improvement_. Botanical Studies_ , 55 : 31. Thomas, H. M., W. G. Morgan, and M. W. Humphreys, 2003 : Designing grasses with a future-combining the attributes of Lolium and Festuca. Euphytica , 133 : 19-26. Vogg, G., S. Fischer, J. Leide, E. Emmanuel, R. Jetter, A. A. Levy, and M. Riederer, 2004 : Tomato fruit cuticular waxes and their effects on transpiration barrier properties: functional characterization of a mutant deficient in a very-long-chain fatty acid beta-ketoacyl-CoA synthase. Journal of Experimental Botany , 55 : 1401-1410. Wang, Z. Y., A. Hopkins and R. Mian, 2001 : Forage and turf grass biotechnology. Crit. Rev. Plant Sci., 20 : 573-619. Williams, W. M. 1987 : Genetics and Breeding. In : White clover, M. J. Baker, W. M. Williams (eds.). CAB Int., Wallingford, Oxon, UK. Wu, Y. Y., Q. J. Chen, M. Chen, J. Chen and X. C. Wang, 2005 : Salt tolerant transgenic perennial ryegrass ( Lolium perenne L.) obtained by Agrobacterium tumefaciens –mediated transformation of the vacuolar Na+^ /H +^ antiporter gene. Plant Science , 169 : 65-73. Yamada, T., J. W. Forster, M. W. Humphreys and T. Takamizo, 2005 : Genetics and molecular breeding in Lolium/Festuca Grass species complex. Grassland Science , 51 : 89-106. Zhang, J. Y., C. D. Broeckling, E. B. Blancaflor, M. K. Sledge, L. W. Summer and Z. Y. Wang, 2005 : Overexpression of WXP 1, a putative Medicago truncatula AP2 domain-containing transcription factor gene, increase cuticular wax accumulation and enhances drought tolerance in transgenic alfalfa ( Medicago sativa ). Plant Journal , 42 : 689-

Zhang, J. Y. and Z. Y. Wang, 2007 : Recent advances in molecular breeding of forage crops for improved drought and salt stress tolerance. In : Advances in Molecular Breeding Toward Drought and Salt Tolerance Crops. Publ. Springer, pp 797-817.

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Forage Res., 45 (1) : pp. 10-22 (2019) http://forageresearch.in

NUTRITIOUS FEED FOR FARM ANIMALS DURING LEAN PERIOD : SILAGE AND HAY-A REVIEW

BALWINDER KUMAR1,^ *, NAVJOT SINGH BRAR 1 , H. K. VERMA 2 , ANIL KUMAR 1 AND RAJBIR SINGH 3

(^1) Krishi Vigyan Kendra, Guru Angad Dev Veterinary and Animal Sciences University, Tarn Taran -143 412, Punjab, India (^2) Directorate of Extension Education, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana-141 004, Punjab, India (^3) ICAR-ATARI, Zone 1, PAU Campus, Ludhiana -141 004, Punjab, India *(e-mail : dr.balwinderkumar@rediffmail.com) (Received : 18 April 2019; Accepted : 16 June 2019)

SUMMARY

Green forages are considered to be the backbone of dairy sector as they play a vital role in transforming dairy farming into a profitable business. So, there is urgent need for preservation of nutrients from green forages including fodder tree leaves available during the flush period for feeding livestock during lean period so that high yielding animals can be sustained for profitable dairy farming. Silage is as nutritious as green fodders as it preserves the nutrients in the original form and hence it is as good for animal feeding as green fodder itself. From a practical view, the three most important things that must occur in order to make good silage are 1) the rapid removal of air, 2) the rapid production of lactic acid that results in a rapid drop in pH, and 3) continued exclusion of air from the silage mass during storage and feed out. In certain forage crops such as maize has relatively low buffering capacity and high concentrations of fermentable carbohydrates; therefore, pH decline is rapid and final pH is usually low, approximately 3.5, thus are more suitable for silage making. In general, the pH of silage at the final stage should be within the range of 3.5-4.3. Berseem and alfalfa has a high buffering capacity in comparison to maize leading to difficulty in lowering pH and making silage from berseem. Proper dry matter in forage should be there so that it can be packed well and more lactic acid is produced. Longer filling time of chaffed fodder in silo might have not maintained anaerobic conditions properly leading to increased aflatoxins in silage. The container in which silage is made is of greatest importance and will determine to the large extent the nature and quality of final product. The most common silo is the trench silo. One cubic meter space can store 5-6 quintals of green chopped fodder. Various types of additives can be used to improve or inhibit the fermentation or supplement nutrients needed by ruminants to be fed as silage. Silage quality is determined by mainly the odour, physical state, pH, ammonia nitrogen, volatile acids and lactic acid. It should be of pleasant smell and semi dry in nature. It should be of green colour. Another way of preserving nutrients is practiced in the form of hay. The principle of hay making is to preserve nutritional value of forages through drying it to a level at which the activity of microbial decomposers is inhibited. Forages can he harvested at the stage of proper nutritive value and be preserved as hay for feeding it during lean period. A moisture content of 10- 12 % is optimum level for halting the microbial activity. It assures the supply of high digestible feed with high protein and caloric values all the year round. Hay making is profitable when the production of fodder is in excess of consumption. Food quality of dried forage (hay) is as nutritious as the green forage (if available) during the period of June-December when high protein forage is scarce. It fetches higher price and helps to increase milk production.

Key Words : Silage, Hay, Lean, Silo pit, Dry matter, Protein

Green forages are considered to be the backbone of dairy farming as they play a vital role in transforming dairy farming into a profitable business. India is basically an agrarian country with large livestock population making dairy and livestock industry an important subsidiary occupation of

farmers. It contributes to the economy of the country by providing milk, meat, wool etc. India has recently emerged as largest producer of milk in the world but livestock productivity is very low as compared to the developed countries. Low productivity of the animals is ascribed chiefly due to inadequate supply of

fodder crop increased as hard stem on fermentation in silage becomes soft, this helps in easy digestion by dairy animals and the anti quality components are either destroyed or lowered during silage fermentation (Chaudhary et al., 2012).

Ensiling-A potential method for conserving nutrients

Ensiling is a process by which fodder or feed is stored in a silo in order to be converted into silage, a more succulent feed for livestock. The principle of ensiling involves the conversion of water-soluble carbohydrates (WSCs) into organic acids (mainly lactic acid) by lactic acid bacteria (LAB) under an anaerobic environment to rapidly reduce the silage pH. As a result, decomposition of the nutrients is inhibited and the storage time of the forage is extended through its preservation from spoilage microorganisms (Zhang et al., 2019). Ensilage has many advantages over the other methods for preservation of nutrients, particularly from forages. Silage is the material produced by controlled fermentation of nutrients under an anaerobic condition. Ensiling of forage requires precautions for proper preservation of nutrients as lack of understanding of the factors associated with ensiling process may produce silage of poor quality leading to the poor animal performances. The fermentation process is governed by microorganism present in fresh herbage or by additives to maintain anaerobic conditions and discourage clostridial growth with minimum loss of nutrients. This process has been used to preserve carbohydrate rich materials, either alone or through fermentation with other materials, as well as storage of protein rich materials used as animals feeds (Machin, 1990).

Ensiling procedure

From a practical view, the three most important things that must occur in order to make good silage are 1) the rapid removal of air, 2) the rapid production of lactic acid that results in a rapid drop in pH, and 3) continued exclusion of air from the silage mass during storage and feed out. Lactic acid producing bacteria ( Lactobacillus plantarum ) present on fresh forage and on silage equipment, are responsible for most of the acid production during fermentation. There is a positive correlation between the number of bacteria present at the time of ensiling and the rate of pH decline (Thomas, 2008). In short, for a rapid and extensive fermentation to occur, the

forage must have high concentrations of fermentable carbohydrates, low buffering capacity, relatively low dry matter content (30-40 %) and adequate lactic acid bacteria present prior to ensiling. Certain forage crops such as maize has relatively low buffering capacity and high concentrations of fermentable carbohydrates; therefore, pH decline is rapid and final pH is usually low, approximately 3.5. In general, the pH of silage at the final stage should be within the range of 3.5-4. (Roth and Heinrichs, 2001). Because of the biochemical changes involved in silage making, the colour of chlorophyll changes to greenish brown due to a pigment called phaeophytin (a magnesium free derivative of chlorophyll). After chopping, plant respiration continues for several hours (and perhaps days if silage is poorly packed) and plant enzymes (e.g., proteases) are active until air is used up. Rapid removal of air is important because it prevents the growth of unwanted aerobic bacteria, yeasts, and molds that compete with beneficial bacteria for substrate. If air is not removed quickly, high temperatures and prolonged heating are commonly observed. Air can be eliminated by wilting plant material to recommended dry matters (DM) for the specific crop and storage structure, chopping forage to a correct length, quick packing, good compacting, even distribution of forage in the storage structure, and immediately sealing the silo. When air is removed lactic acid bacteria utilize water-soluble carbohydrates to produce lactic acid, the primary acid, responsible for decreasing the pH in silage. A quick reduction in silage pH will help to limit the breakdown of protein in the silo by inactivating plant proteases. In addition, a rapid decrease in pH will inhibit the growth of undesirable anaerobic microorganisms such as enterobacteria and clostridia. Airtight silos and removal of sufficient silage during feed-out can help to prevent aerobic spoilage due to limitation of yeast. Berseem and alfalfa has a high buffering capacity in comparison to maize leading to difficulty in lowering pH and making silage from berseem. The dry matter content of the forage can also have major effects on the ensiling process. Proper dry matter in forage should be there so that it can be packed well and more lactic acid is produced. Undesirable bacteria called clostridia tend to thrive in very wet silages and can result in excessive protein degradation, DM loss, and production of toxins. Where weather permits, wilting forage above 30-35% DM prior to ensiling can reduce the incidence of clostridia. Delayed filling of silo pit results in excessive amounts of air trapped in the forage mass can have detrimental effects on the

12 KUMAR, BRAR, VERMA, KUMAR AND SINGH

ensiling process. Longer filling time of chaffed fodder in silo might have not maintained anaerobic conditions properly leading to increased aflatoxins in silage (Brar et al. , 2017). Wittenberg (2004) also reported that with rapid elimination of oxygen, as the corn herbage enters the silo, is critical for the prevention of storage moulds, as subsequent aeration of silage can cause fungi to proliferate and if conditions are suitable, mycotoxin may be produced. Another factor that can affect the ensiling process is the amount of water-soluble carbohydrates present for good fermentation to take place. WSC decreases and DM losses increased when forage was not immediately packed into silos after chopping. The end products of silage fermentation are often monitored to assess silage quality and the composition of “normal silages” is presented in Table 1.

Harvest time for making good quality silage

To prepare best quality silage, cereal green fodder like green fodder maize, fodder sorghum, bajra, Hybrid Napier, sugar cane tops and oat, etc are required. Preference for cereal green fodder (monocotyledons) is due to because of more sugar content than protein, as sugar is utilized in fermentation process to make lactic acid by microorganisms. These cereal fodder crops have hard stem, which takes more time for drying in making hay of these crops, so it is better to use these kinds of crops for making silage than hay. Silage quality and yield are affected by sowing method, cultivar and applied cultural practices (Ileri et. al , 2018). Time of harvest has a major impact on the nutritive value of silage. With advancing crop maturity, protein content, available energy, daily nutrient intake and digestibility decrease while later cutting represents lower carbohydrate and more lignin. Since dry matter yield per unit area are lowered by early harvest, time of harvest is a compromise between nutritive value

and yield. High prices for energy and protein tend to favour early harvest despite of lower dry matter yield. Griffiths et al. (2004) used Milk line score (MLS) to determine the proper stage of harvesting of maize crop. The MLS varies from 0 (no visible milk line at the tip of kernel) to 5 (the milk line reaches the base of the kernel and a black or brown layer forms across it). Maize is best suited to be ensiled when the grains are in the milking stage or at 2.5 milk line score (MLS) i.e. the milk line is halfway down the grain, is considered best stage to harvest maize for silage (Fig. 1). Brar et al , (2017) reported that, for making of good quality silage, harvest the crop at proper stage, when the nutrient contents are at peak i.e. when the grains are in dent stage or near 2.5 MLS.

TABLE 1 Common end products of silage fermentation.

Item Positive or Action (s) Negative

pH + Low pH inhibits bacterial activity Lactic acid + Inhibits bacterial activity by lowering pH. Acetic acid - Associated with undesirable fermentations.

• Inhibits yeasts responsible for aerobic spoilage. Butyric acid - Associated with protein degradation, toxin formation, and large losses of DM and energy. Ethanol - Indicator of undesirable yeast fermentation and high DM losses. Ammonia - High levels indicate excessive protein breakdown Acid detergent insoluble - High levels indicate heat-damaged protein and low energy content. nitrogen (ADIN)

Fig. 1. Right stage for harvesting maize for grain based silage making.

Some important management practices that will help in making high quality silage are listed in Table 2.

Advantages / Disadvantages of Ensiling :

Silage has many advantages over hay and other methods of preservations, chiefly because of less loss of essential nutrients.

• For daily cutting, transporting & chaffing of fodder in traditional way requires more labour and time but in case of silage, fodder cutting, transport, chaffing is done at one time only,

NUTRITIOUS FEED FOR LEAN PERIOD 13

and the length of the feeding period. The different kinds of silo designs are.

1. Stacks
2. Clamp silo
3. Pit silo
4. Trench silo
5. Bunker silo and
6. Tower silo

The most common silo is the trench silo. One cubic meter space can store 5-6 quintals of green chopped fodder. Generally a trench of 10 m x 4 m x 1. m near the cattle shed can store 350-400 quintals of chopped green fodder or one cubic feet pit can accommodate roughly 15 Kg of green fodder. The length and width of trench can vary depending on the number of animals and fodder available for making the silage. The pressing of the material may be carried out manually or mechanically by using a tractor. In case of pressing with tractor, the width of pit should be at least double the width of tractor i.e. 12-15 feet. Depth of pit should be 6-8 feet. Care should be taken that material on the sides and edges are properly compressed. The trench should be high spot so that rain water cannot stagnate near the silo pit. Trench silo has advantages like less air infiltration, less power required for filling the trench, loading and carrying silage is easier. Silo pit should have slanting walls with narrow base and broad opening as such shape helps in maximum exclusion of the air. The silage is made by 1) Direct cut method

2. Wilting method. Wilting method is preferred over direct cut method which as under:

1. Harvested green fodder should be wilted to 65-70 % moisture. Or when harvested at pnper

harvesting stage contains this much moisture.

2. Chop the fodder to make pieces of 2-3 inches so that material is packed well.
3. The walls of the silo pit should be plastered or lined with straw. The chopping should be done near the silo so that the chopping of fodder and filling of silo pit is done simultaneously.
4. Filling should be done in layers of one feet as soon as possible.
5. Pressing of the fodder in the pit should be done regularly to exclude the air.
6. The silo should be filled 1 meter above the ground level and arranged it in the semicircle with dome shaped at top.
7. Cover the pit with one feet thick layer of straw and plaster it with the mud mixed with wheat bhusa to make it air tight and protect it from rains. Alternatively plastic sheet can be used to cover the cut forage.
8. Check the filled pit once a week to avoid cracking of the plaster because any crack in the plastered layer will affect the fermentation process. Silage will be ready within 45 days.
9. Open the silo pit from one side only and take out 25-30 kg silage per animal/day for feeding. The remaining silage kept covered stays good till used.

Nutrient losses during ensilage and steps to Reduce Nutrient Losses:

Generally loss of dry matter, carotenes, carbohydrate and proteins occur due to respiration, fermentation and aerobic deterioration. The other losses of nutrients arise from field, harvesting and affluent losses. The field losses may occur due to shattering of leaves and other nutritious

TABLE 3 Milk production (kg/animal/day) of HF crossbred dairy cows pre and post maize silage feeding

Village Size of Fodder No. of No. of Silage Average milk Average milk Increase silopit stored animals animals in fed yield before after silage milk (m^3 ) (tonnes) early silage feeding production lactation feeding (%) --------------------------------------------------------(Kg/animal/day)-------------------------------------------------------

Mari Kamboke 285 200 35 12 30.0 20.0 23.0 15. Mari Boharwali 596 420 65 13 28.0 22.0 26.0 18. Saidpur 294 190 35 15 30.0 27.0 30.0 11. Kairon 656 460 70 25 35.0 28.0 33.0 17. Kairon 544 380 60 20 35.0 27.0 31.0 14. Thattian khurd 351 230 50 15 32.0 25.0 29.0 16. Mean -- -- -- 31.7 24.8 28.7 15.

Source : Brar et al., 2016.

NUTRITIOUS FEED FOR LEAN PERIOD 15

portions because of poor harvesting managements. The extent of loss in dry matter depends on the time at which the forage is ensiled. Over the period of 48 hours, losses of DM may occur which may be as high as 6.4 percent after 5 days. Loss of carbohydrates and protein also occur due to respiration and proteolysis by plant enzymes. Studies have been revealed that the loss of nutrients during ensilage was drastically minimized with increasing dry matter content of ensiling material (Chaudhary et al., 2014). The fermentation losses chiefly depend upon the moisture content. The clostridial type fermentation is deleterious for most of the nutrients. The clostridia are responsible for the loss of protein. Losses thus are dependent upon pH, moisture content of siling material and type of micro-organism growing during course of fermentation. Forages of low dry matter content (less than 22.9%) leads to effluent production with a considerable loss of nutrients (Castle and Watson, 1993). After the silo is opened for feeding to livestock, the silage surface is exposed to air and thus leading to aerobic secondary fermentation. During aerobic degradation, the temperature and pH rises while lactic acid content reduces. Loss of DM and nitrogenous substances occur due to escape of volatile fatty acid, lactic acid and ammonia. Aerobic deterioration of silage can cause problems for human due to transfer of pathogens and mycotoxins from the silage to other feeds and animal products such as milk (Ogunade et al , 2016). Loss of nutrients arising out of secondary fermentation could be 0-15 % and could be minimized by management practices such as use of cover, propionic acid etc (Wyss, 2000). The Table 4 below summaries the losses of nutrients during preservation of herbages as silage. Reduction in the nutritive value of silage fermentation with respiratory losses, silage heating and clostridial fermentation is minimized by limiting air and moisture contact with silage (Bolsen et al , 1996). Minimizing oxygen exposure to silage is essential for obtaining good quality silage. Air allows the respiration process to continue using soluble carbohydrates essential for acid production, which generates heat and increases the temperature. Process of respiration results in loss of valuable dry matter and energy. Air exposure during preservation tends to progress towards mould formation and leading to rottened silage. The increase in the temperature of silage as a result of heating also reduces its palatability when fed to livestock (Pelz and Hoffman, 1997). Uniformly compacted silage and properly sealing aid in air exclusion.

Dry matter concentration of the forages plays a vital role in minimizing the nutrient losses during ensilage. High moisture silage leads to clostridial fermentation, which cause excessive dry matter loss, high butyric acid concentration and lower nutrient intake (Henderson and Mc Donald, l971). Proper stage of harvesting and dry mater content maximizes the nutritive value of silage (Mojumdar and Rekib, 1980; Brar et al , 2017). Chahine et al. (2009) reported that 30.0-40.0% dry matter content is optimum for corn silage for better quality and for the production of livestock. Wilting of high moisture forage to 30% dry matter is a safe way, which inhibits the clostridial fermentation. Clostridia bacteria degrade sugars and also convert lactic acid to butyric acid and elevate ammonia concentration and thus causing pH to rise. They also break down protein to amines. Thus, clostridial fermentation has an undesirable effect on the nutrient leading to their decomposition to undesirable end products, dry matter loss and reduced palatability (Nikolic and Jovanovic, 1986). The heat caused during fermentation plays vital role in preservation of nutrients. Higher temperature silage (100ºF) has been found to be poor in quality. The over heated silage produced at a temperature above 120ºF have been found to be resulting into heat damaged protein having brown to dark brown colour with a tobacco type fowl smell. Protein of heat-damaged silage forms a complex with carbohydrates and is not digestible. The part of protein and energy is not available to livestock and resulting into lower DCP and TDN values (Redriguez et al , 1985). Higher temperature also increases aerobic spoilage and reduces stability of silage. Water soluble carbohydrate content of forages constitutes the primary nutrient that is fermented to lactic acid and acetic acid by Lactobacillus bacteria to produce a low pH (4.5) and stable silage. Maize, sorghum, oat and other cereal fodders usually have higher soluble sugar concentration and a good stable

TABLE 4 Nutritive Losses During Silage making

Biological process Judgment Approx loss (%)

Respiration Unavoidable 1- Fermentation Unavoidable 1- Effluent Mutual 5- Pre-wilting Unavoidable 2- Secondary fermentation Avoidable 0- Aerobic transformation Avoidable 0- Total losses 7-

Source : Mojumdar (2009).

16 KUMAR, BRAR, VERMA, KUMAR AND SINGH