Whole cottonseed and palmitic and oleic acid supplementation improve production responses during the immediate postpartum in multiparous dairy cows

We evaluated the effects of whole cottonseed (WCS) and fatty acid (FA) supplementation on the production responses of early-lactation cows. Fifty-two multiparous cows were used in a randomized complete block design with a 2 × 2 factorial arrangement of treatments. The following treatment diets were fed from 1 to 21 d postpartum (fresh period; FR): (1) a diet containing no WCS or supplemental FA (CON); (2) a diet containing WCS at 10% diet DM (CT); (3) a diet supplemented with a calcium salt containing 60% C16:0 and 30% cis-9 C18:1 (FAT); and (4) a diet containing WCS at 10% diet DM and a C16:0 cis-9 C18:1 calcium salt (CT+FAT). In the WCS-containing diets, WCS replaced soybean hulls and soybean meal. The FA supplement was added at 1.9% of diet DM to deliver ∼1.5% of FA and replaced soyhulls in the CT and CT+FAT treatments. During the carryover period (CO; 22-42 d postpartum), all cows were offered a common diet to evaluate the carryover effects of the treatment diets. During the FR period, WCS and FA supplementation interacted with time to affect plasma nonesterified fatty acids. During FR period, WCS and FA supplementation interacted to affect DMI, NDF intake, the yields of milk fat and 3.5% FCM, and plasma BHB, and tended to interact to modify the yield of ECM and milk energy output. The CT treatment increased DMI compared with CON and FAT. The CT, FAT, and CT+FAT treatments increased the yields of 3.5% FCM and milk fat and tended to increase the yield of ECM and milk energy output compared with CON. However, when WCS and the supplemental FA were fed together, no further improvement was observed in milk production responses compared with when they were fed separately. Whole cottonseed and time tended to interact to modify plasma insulin. Overall, WCS increased DMI, most of the milk production responses, energy intake, and plasma gossypol; reduced 18-carbon and total FA digestibility; and tended to reduce NDF digestibility. Overall, FA increased feed efficiency, milk fat content, and plasma gossypol; tended to increase milk fat yield; and tended to reduce milk protein content. We did not observe treatment differences for BW, BCS, BW change, and BCS change during the FR period. During the CO period, FA tended to reduce BW loss. The absence of a synergistic or additive effect when feeding both WCS and supplemental FA could be attributed to their lack of effect on DMI and reduced digestibility of NDF and FA. In conclusion, these results suggest that both WCS and supplemental FA in the diet can enhance milk production in early-lactation dairy cows, with WCS improving milk fat and protein yields and supplemental FA improving milk fat yield.