Heat Stress Alleviation in Boars and Lactating Sows by Betaine Supplementation and Floor Cooling

Francisco Cabezon, Purdue University

Abstract

Continuous genetic selection during the last decades has been successful at increasing litter size and milk production in sows. Unfortunately, such genetic selection has increased the sow’s heat production making them more sensitive to high ambient temperatures and humidity. A model of heat production in lactating sows was developed, and indicated that there is substantial variation in heat production from sow to sow primarily due to daily feed intake and milk production. The effects of dietary betaine supplementation on lactation and post-lactation performance were evaluated during summer conditions. Sows were supplemented with either 0.00 or 0.21% dietary betaine (193 and 175 sows, respectively). Betaine supplemented sows had 3.90% greater average daily feed intake (ADFI) during lactation than control sows (P = 0.005). Treatment by parity interactions were significant for ADFI and BW loss ( P < 0.008). Parity 2 betaine supplemented sows had 0.72 kg/d greater ADFI and 6.70 kg less BW loss than parity 2 control sows (P < 0.022). Betaine supplemented sows had greater ADFI on 6-11, 12-16, and 17-21 d periods (P < 0.019). Wean to estrus intervals (WEI) were 0.31 d shorter (P = 0.004) and had a different distribution (P = 0.029) for betaine supplemented than control sows. Greater percentages, 3.2 and 12.1% of betaine supplemented sows returned to estrus on d 3 and 4 than control sows. In another study, the effects of betaine supplementation on signs of heat stress and follicular development were investigated. Sows supplemented with 0.21% dietary betaine had 0.51 mm greater follicle diameter (P = 0.043), and 0.23°C lower rectal temperature (P = 0.048) than control sows. The effects of dietary betaine supplementation at 3 concentrations 0.00%, 0.63% or 1.26% (32, 27, and 30 boars, respectively) were evaluated on semen characteristics, quality and quality after storage on boars. Serum homocysteine concentrations were less for animals with betaine dietary treatments (P = 0.016). Betaine supplementation tended to increase total sperm in the ejaculates (approximately 5 to 10 billion sperm/ejaculate) when collectively compared with data of the control animals (P = 0.093). Sperm morphology analysis indicated there was a greater percent of sperm with distal midpiece reflex (P = 0.022) and tail (P = 0.091) abnormalities in boars fed the betaine 1.26% diet. Betaine concentration in the seminal plasma was greater in boars with betaine treatments, with animals being fed the 0.63% and 1.26% betaine diets having 59.2% and 54.5% greater betaine concentrations in seminal plasma as compared with boars of the control group (P = 0.046). In another study, the effects of floor cooling on sow’s responses to heat stress were evaluated during an acute heat stress (mean room temperature: 35.1 ± 0.4°C and relative humidity: 68.4 ± 3.2%). Four constant cool water flow rates of 0.00 (CONTROL, 4 sows), 0.25 (LOW, 2 sows), 0.55 (MEDIUM, 2 sows) or 0.85 (HIGH, 2 sows) L/min were evaluated for 100 min during 8 repetitions. The treatments impacted respiration rates (RR), vaginal temperatures (VT), skin temperatures (ST), and rectal temperatures (RT) after 80 min of cooling. The mean RR were 122, 76, 67, and 45 breaths/min for the CONTROL, LOW, MEDIUM, and HIGH flow rate treatments, respectively (P < 0.001). After 80 min of cooling, the mean VT, RT, and ST were 40.1, 40.0, and 39.4°C for the CONTROL; 39.5, 39.5, and 39.0°C for the LOW; 39.4, 39.2, and 38.9°C for the MEDIUM; and 39.2, 39.0, and 38.6°C for the HIGH flow rate treatment, respectively (P < 0.001). In conclusion, betaine supplementation alleviated some of the negative effects of heat stress in sows. In contrast, cooling pads had a greater impact in alleviating the heat stress signs in sows. Further studies are needed to refine the use of cooling pads and potential dietary treatments, alone or in combinations. Additionally, the effects of environmental temperatures, parity, day of lactation and variation in sows heat production must be taken into account.

Degree

Ph.D.

Advisors

Schinckel, Purdue University.

Subject Area

Animal sciences

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