Genetic Variance of Proteolytic Activity in Alfalfa Herbage

Bowley, S. R.; McKersie, Bryan D.

doi:10.4141/cjps87-019

Cited by 2 publications

(3 citation statements)

References 3 publications

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“…1d are those with the lowest NPN concentration. Of the three populations evaluated by Bowley and McKersie (1987), OAC Minto was identified as the best choice for selection for low proteolysis because of its low mean and a wide range within the population. This choice agrees with the results of the present study; OAC Minto was in Group 2 of Fig.…”

Section: Discussionmentioning

confidence: 99%

“…This variability, although limited, could be used in genetic selection for the reduction of protein degradation in alfalfa silage. However, in the short term, rapid lowering of silage pH through the use of bacterial inoculants or acid additives will likely remain the most effective means of controlling protein degradation in alfalfa silage (McKersie 1985;Bowley and McKersie 1987).…”

Section: Discussionmentioning

confidence: 99%

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Proteolysis in alfalfa silages made from different cultivars

Tremblay¹,

Bélanger²,

McRae³

et al. 2001

Can. J. Plant Sci.

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R. 2001. Proteolysis in alfalfa silages made from different cultivars. Can. J. Plant Sci. 81: 685-692. During silage fermentation, proteolysis reduces the nutritional value of N, particularly in alfalfa. This study evaluated the proteolysis of 27 alfalfa cultivars seeded in triplicate in 2 consecutive years. Forage from each plot was wilted to a targeted dry matter (DM) content of 250 g kg -1 and ensiled in laboratory silos. Minisilos were made with spring growth and summer regrowth in the first year of production for the first seeding, and with the first 2 yr of production for the second seeding, giving 3 harvest years altogether. Concentrations of NPN, NH 3 , FAA, DM, TN, and pH were measured in silages, whereas RUP concentration was evaluated in forages. Low NPN concentration indicates low proteolysis during silage fermentation. Spring growth and summer regrowth were analyzed separately by ANOVA as a completely randomized block design replicated over 3 harvest years. A principal component analysis was then performed on the ANOVA means. Silage DM was used as covariate when it was deemed appropriate. There was a significant variation among cultivars for NPN concentration in silages made of summer regrowth; it varied from 612 to 717 g kg -1 of TN. Concentration of NPN was significantly lower for cultivars WL 225, Rangelander, Iroquois, and WL 222, and higher for cultivars Oneida VR, Arrow, Vernal, Spredor 2, and Armor. Oneida VR and Rangelander had respectively high and low silage NPN concentration in both spring growth and summer regrowth. From cultivars with low silage NPN concentration, Rangelander was the only one with high forage RUP concentration in both spring growth and summer regrowth; proteins in this cultivar would be more resistant to microbial degradation during ensiling and in the rumen.Key words: Non protein nitrogen; proteolysis; alfalfa silage; cultivars Tremblay, G. F., Bélanger, G., McRae, K. B. et Michaud, R. 2001. Protéolyse dans l'ensilage de luzerne fait de différents cultivars. Can. J. Plant Sci. 81: 685-692. Au cours de la fermentation du fourrage en ensilage, la protéolyse réduit la valeur nutritive de l'azote, et ce particulièrement chez la luzerne. Cette étude avait pour but d'évaluer la protéolyse chez 27 cultivars de luzerne semés en triplicata au cours de deux années consécutives. Le fourrage de chaque parcelle était séché jusqu'à un taux visé de matière sèche (MS) de 250 g kg -1 puis ensilé en mini-silos. L'ensilage a été fabriqué en première et deuxième coupe de la première année de production du premier semis et au cours des deux premières années de production du deuxième semis; ce qui représente un total de trois années de récolte. Les concentrations en azote non protéique (NPN), ammoniaque (NH 3 ), acides aminés libres (FAA), MS, azote total (TN) et le pH ont été mesurés dans l'ensilage alors que la concentration en protéines non dégradables dans le rumen (RUP) a été estimée dans le fourrage. Une faible concentration en NPN était considérée comme un indicateur d'une faible pr...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Proteolysis in alfalfa silages made from different cultivars

Tremblay¹,

Bélanger²,

McRae³

et al. 2001

Can. J. Plant Sci.

View full text Add to dashboard Cite

show abstract

“…These data suggested that differences in ruminal protein degradation among forage legumes is only partly explained by tannin concentrations. It should be noted that small genetic differences in proteolysis in silage (Bowley and McKersie, 1987) and in ruminal protein degradability were found in alfalfa germplasm (Broderick and Buxton, 1991). In the future, genetic selection or genetic engineering may be used to produce forages with improved protein efficiency.…”

Section: Improving the Nutritional Value Of Legume Forage Proteinsmentioning

confidence: 99%

Desirable characteristics of forage legumes for improving protein utilization in ruminants.

Broderick

1995

Journal of Animal Science

151

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Forages help meet the protein requirements of ruminants by providing degraded CP for microbial protein synthesis plus protein that escapes ruminal degradation. Evidence from numerous feeding studies with lactating dairy cows indicates that excessive ruminal protein degradation may be the most limiting nutritional factor in higher-quality temperature legume forages. Hence, there is interest in identifying factors that influence the rate and extent of ruminal degradation of forage proteins. Condensed tannins found in legumes are known to decrease protein degradation, either by altering the forage proteins or by inhibiting microbial proteases. Quadratic regressions of degradation rate and estimated protein escape on tannin concentration reached minimal rate (.048/h) and maximal escape (56%) at 27 g of tannic acid equivalents/kg of DM. Although most tannin-containing forages are not well-adapted to growing conditions in North America, biotechnology has been used to inject genes for tannins into adapted germplasm. The CP in red clover, which has no detectable tannins, was found to be less degradable than that in alfalfa, both in the silo and in the rumen. Small differences in protein degradability also were detected among alfalfa germplasm. Protein in alfalfa harvested as hay, rather than as silage, was used more efficiently for milk protein synthesis when fed to lactating cows; degraded CP from hay was captured more efficiently by ruminal microbes for protein synthesis in vitro. A ruminal escape of approximately 35% for total dietary CP is recommended by the NRC for lactating dairy cows fed mixed diets with 1.6 to 1.7 Mcal of NE1/kg of DM. Ruminal degradation of CP from the forage portion of the diet can exceed 65% when forages are the major source of degradable protein. When ruminants obtain most or all of their nutrients from forage, the ruminal escape for forage protein should approximate 35%.

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Genetic Variance of Proteolytic Activity in Alfalfa Herbage

Cited by 2 publications

References 3 publications

Proteolysis in alfalfa silages made from different cultivars

Proteolysis in alfalfa silages made from different cultivars

Desirable characteristics of forage legumes for improving protein utilization in ruminants.

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