Submitted to: Journal of Dairy Science
Publication Type: Abstract only
Publication Acceptance Date: 3/10/2008
Publication Date: 7/7/2008
Citation: Pires, J.A., Benevenga, N.J., Broderick, G.A., Grummer, R.R. 2008. Effect of abomasal infusion of formate on milk protein of cows fed a methionine-deficient diet [abstract]. Journal of Dairy Science. 91(suppl. 1):267. Interpretive Summary:
Technical Abstract: Carbon from formate is transferred to the methyl group of Met in milk protein via the folate cycle. We hypothesized that post-ruminal formate infusion to dairy cows would partially compensate for dietary Met deficiency and enhance milk protein production. Six midlactation cows were used in a balanced replicated 3x3 Latin square design, with 7-d periods and sample collection during the last 4 d of each period. Treatments were continuous abomasal infusions of L-Met (20 g/d; positive control), sodium formate (3x molar amount of L-Met; requirements for methyl groups may be 2 to 4x that for methionine in support of protein synthesis), or sodium acetate (1/2 molar amount of formate, to provide equal amount of carbon; negative control). Cows consumed a diet deficient in metabolizable Met and Lys (18 g/d and 25 g/d, respectively, for a cow producing 40 kg milk/d; estimated from NRC, 2001) ad libitum for at least 4 wk prior to treatment administration. One wk prior to initiation of abomasal infusions, feed was offered at a rate to meet requirements for milk produced the previous 7 d. L-Lys was mixed with each treatment (25 g/d), leading to an estimated total supply of 2.4% Met and 7.1% Lys (MP basis). As expected, Met infusion increased milk protein percent, but protein yield was not different, probably due to greater variability in milk production. Formate did not differ from acetate for any of the measurements. The formate infusion rate may have been insufficient to elicit a production response. Formate may also have been catabolized by gastrointestinal tract, or it may have been diverted to other intermediates of the folate cycle in the liver.