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

View Article: PubMed Central - PubMed

ABSTRACT

Simple summary: Heat 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.

Abstract: Heat 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.

No MeSH data available.


Related in: MedlinePlus

Plasma (a) glucose and (b) non-esterified fatty acid (NEFA) concentrations during thermoneutral (TN) (□) or heat (HE) (■) conditions in sheep (Merino ewe’s, n = 6 sheep per group) fed either 0, 2 or 4 g betaine/day for 21 days (data pooled across days for presentation). The p-values for the effects of environmental temperature and dietary betaine on plasma glucose were 0.49 and 0.95, respectively. The p-values for the effects of environmental temperature and dietary betaine on plasma NEFA were 0.66 and 0.05, respectively. The sed presented is for the interaction between temperature and dietary betaine. There were no significant 2- or 3-way interactions (p > 0.4). See text for description of day effects.
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animals-06-00051-f002: Plasma (a) glucose and (b) non-esterified fatty acid (NEFA) concentrations during thermoneutral (TN) (□) or heat (HE) (■) conditions in sheep (Merino ewe’s, n = 6 sheep per group) fed either 0, 2 or 4 g betaine/day for 21 days (data pooled across days for presentation). The p-values for the effects of environmental temperature and dietary betaine on plasma glucose were 0.49 and 0.95, respectively. The p-values for the effects of environmental temperature and dietary betaine on plasma NEFA were 0.66 and 0.05, respectively. The sed presented is for the interaction between temperature and dietary betaine. There were no significant 2- or 3-way interactions (p > 0.4). See text for description of day effects.

Mentions: There was no effect of environmental temperature (p = 0.49) or dietary betaine (p = 0.95) on plasma glucose concentrations (Figure 2a). However, there was an effect of day on plasma glucose (p = 0.008) such that concentrations decreased with experimental day (data not shown). Plasma glucose concentrations were not influenced by an interaction between temperature, dietary betaine and sample day (p = 0.43). There was no effect of environmental temperature (p = 0.66) on plasma NEFA concentrations, whereas plasma NEFA were decreased by dietary betaine treatment (80, 55 and 54 μmol/L for 0, 2 and 4 g betaine/day, respectively; p = 0.05, Figure 2b). There was an effect of day on plasma NEFA such that plasma NEFA were greater (p = 0.004) on day 19 (the last day of sampling) than they were on previous days although there was no consistent pattern (i.e., there was not a consistent decrease across sample days) and plasma NEFA concentrations varied with sample day (data not shown). Plasma NEFA concentrations were not influenced by an interaction between temperature, dietary betaine and sample day (p = 0.52).


Dietary Betaine Impacts the Physiological Responses to Moderate Heat Conditions in a Dose Dependent Manner in Sheep
Plasma (a) glucose and (b) non-esterified fatty acid (NEFA) concentrations during thermoneutral (TN) (□) or heat (HE) (■) conditions in sheep (Merino ewe’s, n = 6 sheep per group) fed either 0, 2 or 4 g betaine/day for 21 days (data pooled across days for presentation). The p-values for the effects of environmental temperature and dietary betaine on plasma glucose were 0.49 and 0.95, respectively. The p-values for the effects of environmental temperature and dietary betaine on plasma NEFA were 0.66 and 0.05, respectively. The sed presented is for the interaction between temperature and dietary betaine. There were no significant 2- or 3-way interactions (p > 0.4). See text for description of day effects.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5035946&req=5

animals-06-00051-f002: Plasma (a) glucose and (b) non-esterified fatty acid (NEFA) concentrations during thermoneutral (TN) (□) or heat (HE) (■) conditions in sheep (Merino ewe’s, n = 6 sheep per group) fed either 0, 2 or 4 g betaine/day for 21 days (data pooled across days for presentation). The p-values for the effects of environmental temperature and dietary betaine on plasma glucose were 0.49 and 0.95, respectively. The p-values for the effects of environmental temperature and dietary betaine on plasma NEFA were 0.66 and 0.05, respectively. The sed presented is for the interaction between temperature and dietary betaine. There were no significant 2- or 3-way interactions (p > 0.4). See text for description of day effects.
Mentions: There was no effect of environmental temperature (p = 0.49) or dietary betaine (p = 0.95) on plasma glucose concentrations (Figure 2a). However, there was an effect of day on plasma glucose (p = 0.008) such that concentrations decreased with experimental day (data not shown). Plasma glucose concentrations were not influenced by an interaction between temperature, dietary betaine and sample day (p = 0.43). There was no effect of environmental temperature (p = 0.66) on plasma NEFA concentrations, whereas plasma NEFA were decreased by dietary betaine treatment (80, 55 and 54 μmol/L for 0, 2 and 4 g betaine/day, respectively; p = 0.05, Figure 2b). There was an effect of day on plasma NEFA such that plasma NEFA were greater (p = 0.004) on day 19 (the last day of sampling) than they were on previous days although there was no consistent pattern (i.e., there was not a consistent decrease across sample days) and plasma NEFA concentrations varied with sample day (data not shown). Plasma NEFA concentrations were not influenced by an interaction between temperature, dietary betaine and sample day (p = 0.52).

View Article: PubMed Central - PubMed

ABSTRACT

Simple summary: Heat 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.

Abstract: Heat 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.

No MeSH data available.


Related in: MedlinePlus