Yeast culture increased plasma niacin concentration, evaporative heat loss, and feed efficiency of dairy cows in a hot environment

Abstract

The supplementation of dairy cows with yeast culture may increase diet digestibility, plasma niacin concentration, heat dissipation, and lactation performance. Our objective was to evaluate the response of Holstein cows in late lactation (234 ± 131 d in milk) to dead yeast culture (YC, 15 g/d, Factor SC, GRASP, Saccharomyces cerevisiae) during Brazilian summer (temperature-humidity index >68 for 92.2% of the time). Thirty-two cows were individually fed a standard total mixed ration for 14 d and control (CTL) or YC treatments for 35 d, in a covariate adjusted complete randomized block design. Response was evaluated in wk 5 or as repeated measures over time. Cows were milked 3 times per day and treatments (YC or placebo) were orally dosed to each cow before each milking. Plasma niacin was 1.50 for CTL and 1.66 µg/mL for YC. The YC reduced rectal temperature, respiration rate, and skin temperature, whereas it tended to increase sweating rate. The proportion of cows with rectal temperature ≥39.2°C on CTL and YC was, respectively, 8 and 0% at 0730 h, 52 and 25% at 1500 h, and 35 and 26% at 2200 h. Plasma glucose was increased by YC. The total-tract apparent digestibility of nutrients, plasma urea N concentration, molar proportion of ruminal VFA, and urinary allantoin excretion were not affected by YC. Cows fed YC were less selective against feed particles>19 mm in the morning, in the afternoon were more selective against long feed particles and in favor of particles <8 mm, and refused short particles at night. Milk yield was not different (30.5 kg/d for CTL and 30.2 kg/d for YC). Feeding YC reduced dry matter intake (20.3 vs. 19.4 kg/d) and the digestible organic matter intake (15.6 vs. 13.9 kg/d). The inclusion of YC increased the ratios of milk to dry matter intake (1.50 vs. 1.64) and energy-corrected milk to dry matter intake (1.81 vs. 1.98). The covariate adjusted body weight (648 kg) and body condition score (3.0) did not differ. Milk solids yields and concentrations, linear somatic cell count, and milk urea N were also similar. The supplementation of YC increased plasma niacin concentration, body heat loss, and feed efficiency of late lactation dairy cows by reducing intake at similar milk yield.

Effects of feeding live yeast at 2 dosages on performance and feeding behavior of dairy cows under heat stress

“…In fact, supplementing LY to dairy cows in the present experiment improved digestion of fiber and CP, which resulted in increased OM digestion and improved yield of ECM and efficiency of feed conversion into ECM and FCM in heat-stressed dairy cows. These results corroborate those of past studies, in which cows under heat stress fed diets supplemented with LY showed increased yields of milk, FCM, or feed efficiency (Moallem et al, 2009;Dias et al, 2018c), or in which cows fed YC showed improved yield of milk or feed efficiency (Schingoethe et al, 2004;Bruno et al, 2009).…”

“…A few experiments have suggested that microbial additives have the potential to alleviate signs of heat stress (Huber et al, 1994;Salvati et al, 2015;Dias et al, 2018c). In particular, LY or a mixture of LY with YC reduced respiration rate and rectal and skin temperatures (Salvati et al, 2015;Dias et al, 2018c), benefits partially attributable to changes in plasma concentrations of niacin and improved evaporative heat loss (Dias et al, 2018c). It is possible that the effects of LY on regulation of body temperature and responses to heat stress are influenced by the strain and amount of S. cerevisiae supplemented.…”

“…It is possible that the effects of LY on regulation of body temperature and responses to heat stress are influenced by the strain and amount of S. cerevisiae supplemented. Dias et al (2018c) supplemented dairy cows with a YC containing only dead S. cerevisiae cells (total of 2.85 × 10 10 cfu of dead cells/cow per day), and Salvati et al (2015) supplemented cows with a mixture of 25 × 10 10 cfu of live cells and 5 × 10 10 cfu of dead cells/cow per day. These amounts are 2 to 17 times greater than those fed in treatment 0.5 g/d and almost 7 times more than the dose of S. cerevisiae fed in treatment 1 g/d.…”

Strategies for increasing fertility in high productivity dairy herds

“…Likewise, it has also been described that the reduction in dry matter intake (Dias et al, 2018), can prolong after calving negative energy balance and calving-conception interval. The reduction in dry matter intake and the prolongation of the negative energy balance promotes a decrease in plasma insulin, glucose, and IGF-I concentrations and increases the plasma concentration of growth hormone (GH) and nonesterified fatty acids.…”

“…Another effect of heat stress is the change in the patterns of ovarian follicular development and the gene expression in the oocyte (Ferreira et al, 2016). Likewise, it has also been described the reduction in dry matter intake (Dias et al, 2018), which in turn can prolong after calving negative energy balance and calving-conception interval. Finally, many researches have been carried out in the areas of genetics, physiology, nutrition, management, and applications of reproductive biotechnology in the last decade, to minimize the impact of high productivity on the reproductive rates of dairy cows.…”