The Effect of Ruminal Bypass Lysine and Methionine on Milk Yield and Composition of Lactating Cows

Abstract

Fifty-six multiparous Holstein cows were assigned at 3 wk prepartum to rations based on grass silage with 1) corn distillers grains to provide 86 and 90% of estimated required metabolizable Lys and Met, respectively; 2) a blend of blood meal, fish meal, and meat and bone meal as amino acid (AA) sources to provide 112 and 103% of required metabolizable Lys and Met, respectively; 3) ruminally protected Lys and Met added as a top-dressing to ration 1 to provide 27 g/d of Lys and 8 g/d of Met as available AA at the duodenum postpartum; and 4) ruminally protected AA for 8 wk postpartum as a top-dressing to ration 1 to provide 40 g/d of Lys and 13 g/d of Met as available AA at the duodenum. Cows fed rations 3 and 4 were offered 13.5 g/d of duodenally available Lys and 4 g/d of duodenally available Met for 3 wk prepartum. The total length of the study was 43 wk. Cows fed ration 4 consumed 3 to 4 kg more dry matter than did cows fed the other three rations, and milk yield and the percentage of milk protein and fat were significantly increased during the first 8 wk of lactation. In early lactation, cows fed ration 3 had a greater milk fat percentage but similar dry matter intake, protein percentage, and yield of 4% fat-corrected milk compared with cows fed ration 2. The concentrations of blood serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase, triglyceride, and nonesterified fatty acids were lower for cows fed ration 4 during the first 8 wk of lactation than they were for cows fed the other three rations. The mammary arteriovenous difference of whole blood AA indicated that Met along with His and Arg may be the most limiting AA for milk yield.

The effect of protected methionine on milk yield and its composition in lactating dairy cows fed grass silage-based diets

“…This effect is a common feature of experiments involving protected forms of methionine (Overton et al, 1996(Overton et al, , 1998Rulquin and Delaby, 1997;Overton et al, 1998;Xu et al, 1998). Moreover, elevated levels of methionine metabolites, such as taurine, were consistent with the results of similar experiments using methionine (Overton et al, 1996;Pisulewski et al, 1996;Rulquin and Delaby, 1997).…”

“…Similarly, postruminal methionine did not affect DMI or milk yield of cows fed with maize silage (Pisulewski i in., 1996;Rulquin and Delaby, 1997) or lucerne-maize silage-based diets (Overton et al, 1996(Overton et al, , 1998. However, in some conditions, supplementing grass silage-based diets with protected (lysine and methionine) amino acids increases DMI (Xu et al, 1998). Since milk yield of dairy cows may be increased by supplemental amino acids in the early stages of lactation, and not in mid-or late lactation (Rulquin, 1992) we did not expect marked changes of these measurement in our studies (Table 3).…”

“…Generally, they were in line with the results of similar studies (Chillard et al, 1995), in which, feeding protected methionine did not significantly alter these parameters. Moreover, marked increases in milk fat yield might be expected only in early stages of lactation as achieved through increasing milk yield (Rulquin, 1992) or both fat content and milk yield (Xu et al, 1998). However, the effects of postruminal supplements of methionine on milk fat synthesis are a matter of controversy.…”

“…7.3% PDI). Therefore, methionine is most likely to limit milk protein yield and/or content, whereas the lysine supply may be sufficient in dairy cows offered grass silagebased rations (Robert et al, 1994;Chillard et al, 1995;Xu et al, 1998).…”

Effect of rumen-protected protein supplemented with three amino acids on milk yield, composition and fatty acid profile in dairy cows

“…Korhonen et al (2000) mentioned His as the first limiting AA in diets based on grass silage and, according to Vanhatalo et al (1999) His has been identified as a potentially limiting AA for milk production. Other authors mentioned as limiting the combinations of Met with Leu (Krober et al, 2001) and/or with His and Arg (Xu et al, 1998). The problem of limiting AA has been relatively well investigated in studies on the supply of Met and Lys but not enough data are available for other AA or their combinations.…”