Milk production, milk composition, and reproductive function of dairy cows fed different fats

Abstract

, H. 2001. Milk production, milk composition, and reproductive function of dairy cows fed different fats. Can. J. Anim. Sci. 81: 263-271. Thirty-five non-gestating multiparous Holstein cows averaging 571 kg of BW (SE = 8) were allotted at 9 wk postpartum to one of two dietary fat supplements based on either Megalac® (Volac Ltd., Roston, Hertfordshire, UK) and solvent extracted flaxseed meal (MEGA) or whole flaxseed treated with formaldehyde (FLAX) to determine the effects on milk production and composition, follicular development, gestation rate, and fatty acid (FA) composition of blood. Cows were fed a total mixed diet based on ryegrass silage and fat supplements for ad libitum intake. The experiment was carried out between weeks 9 and 19 of lactation. Dry matter (DM) intake and change in body weight were similar for cows fed MEGA and FLAX. Milk production was higher for cows fed MEGA than for those fed FLAX (19.8 vs. 18.6 kg d -1 ) as was 4% fat-corrected milk yield (22.9 vs. 20.2 kg d -1 ). Increased fat mobilization could have contributed to increased milk yield when cows were fed MEGA compared with when they were fed FLAX as plasma concentrations of non-esterified FA and cholesterol increased more from weeks 9 to 19 of lactation for cows fed MEGA. Milk fat percentage tended (P = 0.06) to be greater for cows fed MEGA (4.62%) compared with those fed FLAX (4.37%). Milk protein percentage was higher for cows fed FLAX (3.09%) than for those fed MEGA (2.95%), indicating that formaldehyde protection of flaxseed was adequate to partly prevent ruminal degradability of protein in the seed. Milk fatty acid concentrations of C8:0, C10:0, C12:0, C14:0, C14:1, C18:0, C18:3, and C20:5 were higher for cows fed FLAX than for those fed MEGA while the inverse was observed for C16:0, C16:1, C18:1, and C18:2. Cows fed FLAX had lower blood concentrations of C16:0 than those fed MEGA. There was a significant interaction (P < 0.05) between week and diet for C18:0 and C18:2 with a decrease in C18:0 blood concentration for cows fed MEGA and an increase for those fed FLAX between weeks 9 and 19, while the inverse was observed for C18:2. Blood concentrations of C18:1 were similar for both treatments. Conception rate was significantly lower for cows fed MEGA (50.0%) compared to those fed FLAX (87.5%). Diet had no effect on the size of the largest and second largest follicles, or on the difference between the diameter of the largest and second largest follicles. The number of class 1 (1.09 vs. 0.86), 2 (1.33 vs. 0.86), and 3 (1.28 vs. 0.98) follicles was similar for MEGA and FLAX although the total number (3.70 vs. 2.70) of follicles tended (P = 0.09) to be greater for cows fed MEGA than for those fed FLAX. These data suggest that dietary FA have an effect on gestation rate, but this could not be explained by differences in follicle dynamics or number. However, additional trials with greater numbers of animals are needed to confirm the reproductive results.

Effect of dietary energy source on energy balance, production, metabolic disorders and reproduction in lactating dairy cattle

“…First, as discussed before, the type of lipogenic nutrients (chain length and degree of saturation of long chain fatty acids) as well as the type of glycogenic nutrients (rate of fermentation in the rumen) affects the profile of nutrients absorbed from the gastro-intestinal tract which in turn may impact on reproductive parameters. For supplemental lipogenic nutrients, a possible role for fatty acid composition has been suggested and confirmed in several studies [79,130]. Petit et al [79,130] found a difference in conception rate after first insemination and plasma P4 levels between cows fed extracted flaxseed meal (MEGALAC) or whole flaxseed (FLAX).…”

“…For supplemental lipogenic nutrients, a possible role for fatty acid composition has been suggested and confirmed in several studies [79,130]. Petit et al [79,130] found a difference in conception rate after first insemination and plasma P4 levels between cows fed extracted flaxseed meal (MEGALAC) or whole flaxseed (FLAX). They suggested, next to an increased DM intake, a lower daily milk production and a less negative NEB; also the increased concentration of linolenic acid in FLAX could be beneficial by increasing progesterone levels, decreasing prostaglandin levels and consequently increasing conception rate.…”

Review: Feed intake, milk production and milk composition of dairy cows fed flaxseed

“…Feeding ruminally inert fat sources such as calcium salts of fatty acids has been reported to improve fibre digestion (Schauff and Clark 1992), which in turn could increase feed intake. Feeding formaldehyde-treated whole flaxseed, on a dry matter basis, at 6.7% in a diet containing 58.8% ryegrass silage (Petit et al 2002a) or at 17% in a diet containing 83% ryegrass silage (Petit et al 2001) had no effect on dry matter intake of dairy cows in the early stage of lactation. Similarly, feeding formaldehyde-treated ground flaxseed to dairy cows in the mid stage of lactation at either 2.4 or 14.7% of the dietary dry matter had no effect on dry matter intake of cows (Goodridge et al 2001).…”

“…However, cows fed a diet of 17% of formaldehyde-treated whole flaxseed between weeks 9 and 19 of lactation had a 6.1% decrease in milk yield compared with those fed a diet with no flaxseed (Petit et al 2001), although feeding 6.7% formaldehydetreated whole flaxseed to dairy cows in the mid stage of lactation had no effect on milk yield compared with those fed a mixture of fish oil and formaldehyde-treated whole flaxseed, calcium salts of palm oil or flaxseed oil infused in the abomasum (Petit et al 2002a). Moreover, feeding a diet of 2.4 and 4.7% of formaldehyde-treated ground flaxseed had no effect on milk production of cows in the mid stage of lactation (Goodridge et al 2001).…”

Factors affecting embryo survival and strategies to reduce embryonic mortality in cattle

“…Calcium soaps of fatty acids increase pregnancy rate and reduce open days in high-yielding dairy cows (Sklan et al 1991); however, it was shown that the type of fatty acid and not the additional energy provided by the fatty acids stimulates development of large follicles. In a recent study, conception rate was significantly lower for cows fed a dietary fat supplement based on Megalac ® (50%) compared to those fed whole flaxseed treated with formaldehyde (87.5%), a rich source of linolenic acid (Petit et al 2001). Linolenic acid leads to the formation of eicosapentaenoic acid, an inhibitor of synthesis of prostaglandins of the two series.…”