Abomasal or ruminal administration of flax oil and hulls on milk production, digestibility, and milk fatty acid profile of dairy cows.

Four ruminally fistulated primiparous lactating Holstein cows were assigned to a 4 × 4 Latin square design to determine the effects of the site of administration (rumen or abomasum) of flax oil and flax hulls on diet digestibility and milk fatty acid profile of dairy cows. The treatments were 1) oil and hulls administered in the rumen and abomasal infusion of water (RUM/RUM), 2) oil and hulls infused in the abomasum (ABO/ABO), 3) oil administered in the rumen and hulls infused in the abomasum (RUM/ABO), and 4) oil infused in the abomasum and hulls placed in the rumen (ABO/RUM). Cows on the ABO/ABO and RUM/RUM treatments had the highest and lowest amounts of basal dry matter eaten, respectively. Higher dry matter digestibility was obtained when flax oil bypassed the rumen (ABO/ABO and ABO/RUM) compared with when flax oil was administered directly in the rumen (RUM/ABO and RUM/RUM). Apparent digestibility of ether extract was higher when flax hulls were administered in the rumen (RUM/RUM and ABO/RUM) compared with when flax hulls were infused in the abomasum (ABO/ABO and RUM/ABO). The lowest digestibility of acid detergent fiber and neutral detergent fiber was obtained when both flax products were added in the rumen, which may be attributed to the high amount of oil present in the rumen (7.8% of total dry matter input). The lowest yield of 4% fat-corrected milk was obtained for cows on the RUM/RUM treatment, probably as a result of lower dry matter intake and digestibility of fiber. Milk concentrations of protein, fat, total solids, and lactose were similar among treatments. Administration of oil and hulls in the rumen resulted in the highest concentrations of intermediate products of biohydrogenation and total trans fatty acids in milk fat compared with the other treatments. All ratios of n-6 to n-3 fatty acids in milk fat were lower than the 4 to 1 ratio recommended to improve human health. These results suggest that the presence of both flax oil and flax hulls in the rumen decreases 4% fat-corrected milk yield and digestibility but provides a desirable fatty acid profile of milk to enhance consumers' health.

Milk composition, milk fatty acid profile, digestion, and ruminal fermentation in dairy cows fed whole flaxseed and calcium salts of flaxseed oil.

Four ruminally lactating Holstein cows averaging 602+/-25 kg of body weight and 64+/-6 d in milk at the beginning of the experiment were randomly assigned to a 4 x 4 Latin square design to determine the effects of feeding whole flaxseed and calcium salts of flaxseed oil on dry matter intake, digestibility, ruminal fermentation, milk production and composition, and milk fatty acid profile. The treatments were a control with no flaxseed products (CON) or a diet (on a dry matter basis) of 4.2% whole flaxseed (FLA), 1.9% calcium salts of flaxseed oil (SAL), or 2.3% whole flaxseed and 0.8% calcium salts of flaxseed oil (MIX). The 4 isonitrogenous and isoenergetic diets were fed for ad libitum intake. Experimental periods consisted of 21 d of diet adaptation and 7 d of data collection and sampling. Dry matter intake, digestibility, milk production, and milk concentrations of protein, lactose, urea N, and total solids did not differ among treatments. Ruminal pH was reduced for cows fed the CON diet compared with those fed the SAL diet. Propionate proportion was higher in ruminal fluid of cows fed CON than in that of those fed SAL, and cows fed the SAL and CON diets had ruminal propionate concentrations similar to those of cows fed the FLA and MIX diets. Butyrate concentration was numerically higher for cows fed the SAL diet compared with those fed the FLA diet. Milk fat concentration was lower for cows fed SAL than for those fed CON, and there was no difference between cows fed CON and those fed FLA and MIX. Milk yields of protein, fat, lactose, and total solids were similar among treatments. Concentrations of cis-9 18:1 and of intermediates of ruminal biohydrogenation of fatty acids such as trans-9 18:1 were higher in milk fat of cows fed SAL and MIX than for those fed the CON diet. Concentration of rumenic acid (cis-9, trans-11 18:2) in milk fat was increased by 63% when feeding SAL compared with FLA. Concentration of alpha-linolenic acid was higher in milk fat of cows fed SAL and MIX than in milk of cows fed CON (75 and 61%, respectively), whereas there was no difference between FLA and CON. Flaxseed products (FLA, SAL, and MIX diets) decreased the n-6 to n-3 fatty acid ratio in milk fat. Results confirm that flax products supplying 0.7 to 1.4% supplemental fat in the diet can slightly improve the nutritive value of milk fat for better human health.

In vitro metabolism of flax lignans by ruminal and faecal microbiota of dairy cows.

AIMS: To determine the in vitro conversion of plant lignans from two flax products (hull and seed) into the mammalian lignans, enterolactone and enterodiol, by bovine ruminal and faecal microbiota. METHODS AND RESULTS: Flax seeds and hulls were incubated in vitro over a 96-h time course with ruminal or faecal inoculum. Plant lignans in flax seeds and hulls averaged 9.2 and 32.0 nmol mg(-1), respectively. The highest net production of enterodiol at 72 and 96 h of incubation was obtained with flax hulls incubated with faecal microbiota. There was no difference in net production of enterodiol between flax products within the first 24 h of incubation. In general, net production of enterolactone over the 96-h time course was significantly higher for flax products incubated with ruminal than with faecal microbiota. Net production of enterolactone at 72 and 96 h of incubation was greater for flax hulls than flax seeds. CONCLUSIONS: Results of the present experiment suggest that, of the metabolites studied, the main mammalian lignan metabolite produced from flax hulls and seeds by ruminal microbiota is enterolactone while faecal microbiota leads mainly to the net production of enterodiol. SIGNIFICANCE AND IMPACT OF THE STUDY: This research will improve the understanding of the metabolic pathway of mammalian lignans in dairy cows, in order to enable targeted manipulation of their quantities in milk.

Quality of embryos produced from dairy cows fed whole flaxseed and the success of embryo transfer.

The objective of the experiment was to determine the effects of fat supplementation on embryo quality of dairy cows and the subsequent success of embryo transfer into recipient heifers fed the same sources of fat. A total of 30 lactating Holstein cows were allotted on d 18 postpartum to 2 groups of 15 donor cows blocked for similar calving dates. Total mixed diets based on silage and fat supplements were fed for ad libitum intake. On a dry matter basis, diets fed to donor cows contained 7.9% whole flaxseed or 2.8% calcium salts of palm oil and those fed to recipient heifers contained 11.4% whole flaxseed or 4.2% calcium salts of palm oil. The experiment with donor cows was carried out between d 18 and 109 of lactation. The experimental diets were fed to 121 recipient heifers from wk 8 before estrus synchronization and superovulation to d 50 of gestation. Dietary fat fed to donor cows had no effect on the number of viable embryos per cow (3.7 +/- 0.5), the number of degenerated embryos per cow (1.8 +/- 0.4), or the number of unfertilized oocytes per cow (2.1 +/- 0.8). But feeding flaxseed decreased fertilization rate (64.3 vs. 78.4%) and the percentage of grade 1 to 2 embryos (56.5 vs. 74.1%) and increased the embryo degeneration percentage (27.4 vs. 18.2%) compared with feeding calcium salts of palm oil. There was no effect of diets fed to donor cows and those fed to recipient heifers for pregnancy rate of heifers. Supplementation with a rich source of n-3 fatty acids decreased quality of embryos from donor lactating dairy cows compared with feeding calcium salts of palm oil, but had no effect on the subsequent pregnancy rate of heifers receiving frozen grade-1 embryos.