Swanepoel, N; Robinson, PH; ,
Research conducted over the past 50 years has shown that the general health of dairy cows (i.e., immunity and uterine health) as well as pregnancy rates (i.e., fertilization and embryo development) can be improved through enhanced post-ruminal delivery, and absorption, of poly unsaturated fatty acids (PUPA), especially omega-3 (n-3) PUFA. Since flax-seed contains very high concentrations of n-3 PUFA relative to other oilseeds, our objective was to evaluate effects of substituting conventional ration ingredients (mainly Pima cottonseed) with a flax-seed based product 'LinPRO-R' on production, reproduction and health of multiparous Holstein cows through 150 days in milk (DIM). The LinPRO-R is designed to be a rumen stable, free flowing source of n-3 FA created using dry extrusion. Pens of (similar to)315 early lactation cows were offered rations formulated to contain 0 g/kg (NoLin), 25 g/kg (LoLin) and 50 g/kg (HiLin) dry matter (DM) of LinPro. Samples were collected monthly for 5 months after assignment to treatment at 13.4 +/- 0.84 DIM. The DM intake was unaffected by treatment while milk and component yields all increased (P < 0.05) for LinPro fed cows. However milk variables and BCS all had treatment*DIM interactions (P < 0.05) which indicated different responses to the three diets in the 1st (similar to)80 days post treatment assignment. Feeding LinPro successfully transferred dietary n-3 PUFA into milk, with marked increases in the n-3 to n-6 FA ratio versus the NoLin diet, thereby improving the health-related quality of milk to its human consumers. Milk SCC were quadratically affected (P = 0.05) by LinPro feeding, with lowest SCC occurring for the LoLin fed cows, although SCC as linear score was not treatment impacted. In addition, the proportion of cows culled for mastitis were substantively lower in both LinPro fed groups versus the NoLin group, suggesting improved health of LinPro fed cows. The 1st service conception rate was lower (P < 0.05) for both LinPro groups, although 2nd service conception rates were similar among all groups. Rapid and substantial BCS losses observed with the LoLin group in the 1st (similar to)80 DIM was rapidly regained after 85 DIM, and maintained through 150 DIM. Overall, results suggest improved animal health, lower conception rates, higher milk yield and improved nutritional value of milk for both LinPro groups versus the NoLin group. However, the lower 1st service conception rate when feeding flax-seed as LinPro, which is not consistent with many previous studies, suggests that the potential positive effects of higher PUFA absorption on conception rates observed in previous studies were likely negated by higher BCS losses in this study.