PSXIV-15 The effects of body condition score on the milk production and energy balance of transition dairy cows

Our objective was to evaluate the effects of body condition score (BCS) on the milk production and energy balance of transition dairy cows. Seventy-five multiparous dairy cows were separated into four groups according to the BCS, HH (4.25 ± 0.23 and 3.35 ± 0.19 BCS, pre and postpartum, respectively, n = 17), HM (4.14 ± 0.15 and 2.92 ± 0.24, n = 19), MM (3.10 ± 0.21 and 2.78 ± 0.17, n = 23), ML (2.88 ± 0.23 and 2.46 ± 0.19, n = 16). The milk yield, rumen pH, etc., data were collected and analyzed using a one-way ANOVA model in SAS (SAS version 9.4, SAS Institute Inc., Cary, NC, USA). The ML group had a higher milk yield and total solid yield than the MM group (P < 0.05), while the HH and HM groups had no difference with other groups. The HM and ML groups had a higher milk fat content than the MM group (P < 0.05), while the HH group had no difference with other groups. Milk protein content in the HH group was higher than the ML group (P < 0.05). The milk lactose, total solids, urea content in these groups had no difference. The ML group had a higher milk acetone content than the HH group (P < 0.05). The BCS change in the HH and HM groups was higher than the MM and ML groups, and that in the ML group was higher than the MM group (P < 0.05). The rumen pH had no difference within these groups. These findings collectively indicated the prepartum dairy cow with middle BCS would have a more efficient body fat utilization and a better milk production performance. Furthermore, reducing body fat loss is necessary to avoid the negative energy balance.

The Physiological Roles of Vitamin E and Hypovitaminosis E in the Transition Period of High-Yielding Dairy Cows

Levels of alpha-tocopherol (α-Toc) decline gradually in blood throughout prepartum, reaching lowest levels (hypovitaminosis E) around calving. Despite numerous reports about the disease risk in hypovitaminosis E and the effect of α-Toc supplementation on the health of transition dairy cows, its risk and supplemental effects are controversial. Here, we present some novel data about the disease risk of hypovitaminosis E and the effects of α-Toc supplementation in transition dairy cows. These data strongly demonstrate that hypovitaminosis E is a risk factor for the occurrence of peripartum disease. Furthermore, a study on the effectiveness of using serum vitamin levels as biomarkers to predict disease in dairy cows was reported, and a rapid field test for measuring vitamin levels was developed. By contrast, evidence for how hypovitaminosis E occurred during the transition period was scarce until the 2010s. Pioneering studies conducted with humans and rodents have identified and characterised some α-Toc-related proteins, molecular players involved in α-Toc regulation followed by a study in ruminants from the 2010s. Based on recent literature, the six physiological factors: (1) the decline in α-Toc intake from the close-up period; (2) changes in the digestive and absorptive functions of α-Toc; (3) the decline in plasma high-density lipoprotein as an α-Toc carrier; (4) increasing oxidative stress and consumption of α-Toc; (5) decreasing hepatic α-Toc transfer to circulation; and (6) increasing mammary α-Toc transfer from blood to colostrum, may be involved in α-Toc deficiency during the transition period. However, the mechanisms and pathways are poorly understood, and further studies are needed to understand the physiological role of α-Toc-related molecules in cattle. Understanding the molecular mechanisms underlying hypovitaminosis E will contribute to the prevention of peripartum disease and high performance in dairy cows.

Advances in understanding the needs and improving the welfare of transition dairy cows

One of the most challenging time periods in a dairy cow’s life is when she gives birth and transitions into lactation (the ‘transition’ period). This chapter reviews the latest research assessing the welfare of transition cows. The chapter begins by focusing on the biological health of dairy cows before and after giving birth, as cows are at high risk of disease post-calving. It then goes on to discuss the affective states of transition dairy dairy cows, including pain associated with labor and disease. Finally, the chapter concludes by assessing the natural maternal behavior of cows before calving through a case study.