Changes in Plasma T r i g l y c e r i d e F a t t y A c i d s D u r i n g L a c t a t i o n ~ R. W. WALLENIUS and R. E. WHITCHURCH Department of Animal Sciences Washington State University Pullman 99163 ABSTRACT
differences (2, 5) as well as uptake and incorporation of labeled fatty acids into milk fat (2, 6, 9). Plasma from lactating cows probably contains about 8 to 12 mg/dl TG (5, 14) although Raptaael et al. (13) did not detect TG for all groups and Hartmann and Lascelles observed values of 15 to 17 mg/dl (10). Duncan and Garton (7) found that TG accounted for an average of 10% of total fatty acids in plasma in the dry period and about 2% twenty days into lactation. The fatty acid composition of the triglyceride fraction varied markedly between cows on the first and 22nd day of lactation. Studies of lipid and lipoprotein classes have compared (a) dry and lactating cows (10, 13, 16), (b) ketotic or sub-clinically ketotic with normal cows (11, 19), and (c) normal cows with those receiving restricted roughage-high grain (RRHG) rations to stimulate the milk fat depression syndrome (1, 3). There is evidence that methionine or methionine h y d r o x y analog (MHA) could influence lipid metabolism in lactating cows, either in the host tissue or by influencing rumen microbial lipid synthesis (12). As part of a study concerning the effect of MHA and sulfate on milk and milk fat production, we examined triglyceride fatty acids of milk and blood plasma at varying stages of lactation. Production and milk lipids have been reported (17). This paper reports changes in plasma T G F A during the first half of lactation in normal cows.
Total blood plasma lipid and plasma triglyceride fatty acids were analyzed at an average of 33, 89, and 139 days of lactation (ranges 20 to 57, 52 to 129, and 122 to 157 days for periods I, 11, and l i d for 35 Holstein cows in their second or later Lactation. Average milk production in the test periods was 35.7, 30.3, and 25.5 kg/day. Lipid analysis was part of a study comparing methionine hydroxy analog or sulfur for lactating cows with effects of treatment and time separated statistically. Cows fed methionine analog had a lower percent palmitate in the triglyceride fatty acid, but there was no other treatment effect. There were significant changes with time in percent total lipid and triglyceride fatty acid. Total lipid averaged 424, 526, and 529 mg/dl. Average percents of measured triglyceride fatty acid and differences with stage of lactation were: myristic, 2.96; palmitic, 27.52, I>1I or II1; palmitoleic, 2.83, 1>11 or 111; stearic, 38.58, 1
differences (2, 5) as well as uptake and incorporation of labeled fatty acids into milk fat (2, 6, 9). Plasma from lactating cows probably contains about 8 to 12 mg/dl TG (5, 14) although Raptaael et al. (13) did not detect TG for all groups and Hartmann and Lascelles observed values of 15 to 17 mg/dl (10). Duncan and Garton (7) found that TG accounted for an average of 10% of total fatty acids in plasma in the dry period and about 2% twenty days into lactation. The fatty acid composition of the triglyceride fraction varied markedly between cows on the first and 22nd day of lactation. Studies of lipid and lipoprotein classes have compared (a) dry and lactating cows (10, 13, 16), (b) ketotic or sub-clinically ketotic with normal cows (11, 19), and (c) normal cows with those receiving restricted roughage-high grain (RRHG) rations to stimulate the milk fat depression syndrome (1, 3). There is evidence that methionine or methionine h y d r o x y analog (MHA) could influence lipid metabolism in lactating cows, either in the host tissue or by influencing rumen microbial lipid synthesis (12). As part of a study concerning the effect of MHA and sulfate on milk and milk fat production, we examined triglyceride fatty acids of milk and blood plasma at varying stages of lactation. Production and milk lipids have been reported (17). This paper reports changes in plasma T G F A during the first half of lactation in normal cows.
Total blood plasma lipid and plasma triglyceride fatty acids were analyzed at an average of 33, 89, and 139 days of lactation (ranges 20 to 57, 52 to 129, and 122 to 157 days for periods I, 11, and l i d for 35 Holstein cows in their second or later Lactation. Average milk production in the test periods was 35.7, 30.3, and 25.5 kg/day. Lipid analysis was part of a study comparing methionine hydroxy analog or sulfur for lactating cows with effects of treatment and time separated statistically. Cows fed methionine analog had a lower percent palmitate in the triglyceride fatty acid, but there was no other treatment effect. There were significant changes with time in percent total lipid and triglyceride fatty acid. Total lipid averaged 424, 526, and 529 mg/dl. Average percents of measured triglyceride fatty acid and differences with stage of lactation were: myristic, 2.96; palmitic, 27.52, I>1I or II1; palmitoleic, 2.83, 1>11 or 111; stearic, 38.58, 1
