Dietary Betaine Impacts the Physiological Responses to Moderate Heat Conditions in a Dose Dependent Manner in Sheep

Abstract

Simple SummaryHeat stress in sheep initiates physiological methods to dissipate heat that result in decreased production. This study investigated the use of a dietary supplement, the osmolyte betaine fed at two doses (2 or 4 g/day), on the physiological responses to heat in sheep. Heat exposure initiated physiological responses such as an increased rectal temperature and respiration rate as expected, while betaine supplemented at 2 g/day ameliorated these responses. Thus, dietary betaine supplementation may have beneficial effects for sheep exposed to heat.AbstractHeat exposure (HE) results in decreased production in ruminant species and betaine is proposed as a dietary mitigation method. Merino ewes (n = 36, 40 kg, n = 6 per group) were maintained at thermoneutral (TN, n = 18, 21 °C) or cyclical HE (n = 18, 18–43 °C) conditions for 21 days, and supplemented with either 0 (control), 2 or 4 g betaine/day. Sheep had ad libitum access to water and were pair fed such that intake of sheep on the TN treatment matched that of HE animals. Heart rate (HR), respiration rate (RR), rectal (TR) and skin temperatures (TS) were measured 3 times daily (0900 h, 1300 h, 1700 h). Plasma samples were obtained on 8 days for glucose and NEFA analysis. The HE treatment increased TR by 0.7 °C (40.1 vs. 39.4 °C for HE and TN respectively p < 0.001), TS by +1.8 °C (39.3 vs. 37.5 °C, p < 0.001) and RR by +46 breaths/min (133 vs. 87 breaths/min, p < 0.001) compared to TN. The 2 g betaine/day treatment decreased TR (39.8, 39.6 and 39.8 °C, p < 0.001), TS (38.7, 38.0 and 38.5 °C, p < 0.001) and RR (114, 102 and 116 breaths/min for control, 2 and 4 g betaine/day, p < 0.001) compared to control. Betaine supplementation decreased plasma NEFA concentrations by ~25 μM (80, 55 and 54 μmol/L for 0, 2 and 4 g/day respectively, p = 0.05). These data indicate that dietary betaine supplementation at 2 g betaine/day provides improvements in physiological responses typical of ewes exposed to heat stress and may be a beneficial supplement for the management of sheep during summer.

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

“…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 [10] [6]. The reason for the moderation in response to high doses of Bet during HS may be that the stimulation of hepatic metabolism and a resultant upsurge in…”

“…In addition, Bet is an amino acid and has the ability to improve the production performance of different animals [1], such as steers [10] and pigs [11]. These results suggest that betaine has the potential to reduce heat stress by reducing energy expenditure [6], thereby reducing metabolic heat production and maintaining osmotic balance in animals facing heat stress.…”

“…Dairy cows dissipate body heat through their core surfaces and transfer the heat to the environment [5]. Through the environmental modification method, the production performance of dairy cows can be increased, but the cost of this technique is high [6]. The use of feed additive may be a cost-effective and easily accessible method to reduce heat stress in animals, and it can improve the production performance of dairy cows.…”

Muscle metabolism in sheep and cattle in relation to high rigor temperature – overview and perspective

“…In addition, DiGiacomo et al (2014) refer to dietary interventions to reduce heat-induced toughening, with particular emphasis on the potential of betaine (trimethylglycine). Although most studies on betaine as a nutritional supplement have been carried out on pigs and poultry for the purpose of reducing heat stress and improving growth performance, reports for beef have shown that betaine was effective in lowering the incidence of high rigor temperature carcasses (Loxton et al 2007), reducing rectal temperatures under both thermo-neutral and heat-challenging conditions in sheep (DiGiacomo 2011), and reducing heart and respiration rates in sheep (DiGiacomo et al 2012). In addition, Wang et al (2010a) showed that betaine was effective in reducing insulin resistance by decreasing non-esterified fatty acids (NEFA) in dairy cattle; further support for this effect in mice and humans was reported by Wang et al (2010b) and Borgschulte et al (2008).…”

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

“…12 As a zwitterion, betaine holds intracellular water molecules against a concentration gradient; 13 therefore, it exerts an osmoprotective effect on cells 14,15 and has been suggested to be an active substance given to animals exposed to osmotic stress-related disorders. 16 Betaine also acts as a thermoprotectant for bacterial cells, 17 and it serves as a methyl donor 18 and a direct substrate for ruminal microbes. 19,20 It can also stabilize native protein structure and prevent molecular disintegration.…”