Evaluation of dietary betaine in lactating Holstein cows subjected to heat stress

Abstract

Betaine (BET), a natural, organic osmolyte, improves cellular efficiency by acting as a chaperone, refolding denatured proteins. To test if dietary BET reduced the effect of heat stress (HS) in lactating dairy cows, multiparous, lactating Holstein cows (n=24) were blocked by days in milk (101.4±8.6 d) and randomly assigned to 1 of 3 daily intakes of dietary BET: the control (CON) group received no BET, mid intake (MID) received 57mg of BET/kg of body weight, and high dose (HI) received 114mg of BET/kg of body weight. Cows were fed twice daily and BET was top-dressed at each feeding. Cows were milked 2 times/d and milk samples were taken daily for analysis. Milk components, yield, feed intake, and water intake records were taken daily. Rectal temperature and respiration rate were taken 3 times/d at 0600, 1400, and 1800h. Cows were housed in environmentally controlled rooms and were allowed acclimation for 7d at thermoneutral (TN) conditions with a mean temperature-humidity index of 56.6. Cows were then exposed to 7d of TN followed by 7d of HS represented by a temperature-humidity index of 71.5 for 14d. This was followed by a recovery period of 3d at TN. Dietary BET increased milk yield during the TN period. No differences were found between BET and CON in total milk production or milk composition during HS. The increase in water intake during HS was not as great for cows fed BET compared with controls. The cows on CON diets had higher p.m. respiration rate than both MID and HI BET during HS, but lower rectal temperature compared with BET. No difference was found in serum glucose during TN, but cows given HI had elevated glucose levels during HS compared with CON. No differences were found in serum insulin levels between CON and BET but an intake by environment interaction was present with insulin increasing in HI-treated lactating dairy cows during HS. The heat shock response [heat shock protein (HSP) 27 and HSP70] was upregulated in bovine mammary epithelial cells in vitro. Blood leukocyte HSP27 was downregulated at the HI dose under TN conditions and HSP70 was upregulated at the HI dose and this effect was increased by HS. No effect was seen with the MID dose with HSP27 or HSP70. The lack of effect of BET at MID may be associated with uptake across the gut. We conclude that BET increased milk production under TN conditions and was associated with reduced feed and water intake and slightly increased body temperatures during HS of cows fed BET. The effect of BET on milk production was lost during HS with HI BET, whereas serum glucose levels increased during HS.

Betaine Supplementation Improves the Production Performance, Rumen Fermentation, and Antioxidant Profile of Dairy Cows in Heat Stress

“…For example, milk responses to betaine supplementation during heat stress were highest at 15 g betaine per day and, indeed, disappeared at doses above this [2]. Consistent with these results, Hall et al [25] stated that supplementation of betaine at 35 and 70 g/d improved milk production in thermoneutral conditions but not in heat stress. Curvilinear dose responses to betaine supplementation have also been noticed in beef cattle and sheep during HS with improvements at 2 and 15 g betaine per day, respectively [6,10].…”

“…Higher environmental temperature and THI decreased the milk production performance of dairy cows with a log of 1 to 3 days after THI [24]. Hall et al [25] stated that the addition of up to 150 g of betaine per day in TMR increases milk production in a linear manner in thermoneutral conditions. Nevertheless, the impact of betaine supplementation on lactating dairy cows in the hot season, or during the summer season, are more equivocal [2], possibly due to the multifaceted dose-dependent responses to betaine [20].…”

Betaine addition as a potent ruminal fermentation modulator under hyperthermal and hyperosmotic conditions in vitro

“…Betaine, or trimethylglycine, is found naturally in microbes, animals, and plants, and it is highly abundant in sugar beet . As a zwitterion, betaine holds intracellular water molecules against a concentration gradient; therefore, it exerts an osmoprotective effect on cells and has been suggested to be an active substance given to animals exposed to osmotic stress‐related disorders . Betaine also acts as a thermoprotectant for bacterial cells, and it serves as a methyl donor and a direct substrate for ruminal microbes .…”

Betaine Improves Milk Yield in Grazing Dairy Cows Supplemented with Concentrates at High Temperatures

“…Dietary BET increases milk yield in lactating dairy cows under thermoneutral conditions [9,10,11,12]. BET has been shown to partially mitigate against HS in sheep [13], chickens [14,15], and beef cattle [16].…”

“…BET has been shown to partially mitigate against HS in sheep [13], chickens [14,15], and beef cattle [16]. However, the effects on lactating dairy cows during HS are equivocal [11,17], perhaps because of the complex dose-dependent responses to BET in different organs of the body [18].…”