Effect of ambient temperature on mammary gland metabolism in lactating sows1,2

Abstract

Two groups of three multiparous Large White x Landrace sows were used to investigate the direct effect of ambient temperature on mammary gland metabolism. Sows from the first group were exposed to temperatures of 28 degrees C between d 8 and 14 of lactation, and 20 degrees C between d 15 and 21; treatments were reversed in the second group. Four to six d after farrowing, an ultrasonic blood flow probe was implanted around the right external pudic artery and catheters were fitted in the right anterior mammary vein and in the carotid artery. After surgery all sows were fed 3.8 kg/d of a lactation diet. The arteriovenous (AV, mg/L) plasma samples were obtained every 30 min between 0915 and 1545 on d 5 of exposure to ambient temperature; the same day, milk samples were collected at 1630. Additional arterial samples were obtained between 1000 and 1100 on d 1, 4, and 6 of exposure. Milk yield was estimated from the body weight gain of the litter. Elevated temperature tended to reduce BW loss (2.44 vs 1.82 kg/d, P < 0.10), but did not affect milk yield (11.0 kg/d). Glucagon and leptin arterial concentrations increased (12 and 8%, respectively; P < 0.10), but thyroxin and triiodothyronine concentrations decreased (26 and 16%, respectively; P < 0.01) between 20 and 28 degrees C. Expressed as a percentage of total nutrients, AV difference, glucose, amino acids, triglycerides (TG), free fatty acids, and lactate A-V differences represented 60, 20, 11, 8, and 1%, respectively. Exposure to 28 degrees C increased the extraction rate of glucose, TG, and a-amino acid N (13, 8, and 2.5%, respectively; P < 0.10). The extraction rates of essential and nonessential amino acids were not affected by temperature. The right pudic artery mammary blood flow increased (872 vs 945 mL/min, P < 0.05) between 20 and 28 degrees C, whereas milk yield was unaffected by temperature. It is suggested that this apparent inefficiency of the sow mammary gland in hot conditions could be related to an increase of proportion of blood flow irrigating skin capillaries in order to dissipate body heat.

Evaporative snout cooling system on the performance of lactating sows and their litters in a subtropical region

“…In accord with these results other studies showed the same pattern (RENAUDEAU et al, 2003b;WILLIAMS et al, 2013).…”

“…ao desmame do que no TTCS (60,7±1,4kg (QUINIOU & NOBLET, 1999), increase in water intake (RENAUDEAU et al, 2003b), decrease in milk production (QUINIOU & NOBLET, 1999), failures in subsequent reproductive performance of sows (THAKER & BILKEI, 2005), increase piglet mortality by crushing and decrease piglet weight gain (MARTINS et al, 2008).…”

Resfriamento do piso da maternidade para porcas em lactação no verão

“…Resultados semelhantes foram observados por Lewis et al (1978), Noblet & Etienne (1989), Barb et al (1993), De Bragança et al (1998, Noblet & Etienne (1998), Renaudeau et al (2003) e Moreira (2003), que também constataram que a melhoria na condição ambiental de porcas lactantes resulta em aumento do ganho de peso de leitões. Recentemente, Wagenberg et al (2006), em estudo para avaliar o efeito do resfriamento do piso sobre o desempenho de porcas lactantes, também verificaram que os leitões provenientes de porcas mantidas sobre piso com resfriamento recebendo ração à vontade cresceram 22 g/dia a mais que os leitões das porcas mantidas em piso sem resfriamento.…”

“…De forma semelhante, Carvalho (1981), Schoenherr et al (1989), Lorschy et al (1991), De Bragança et al (1998, Quinou & Noblet (1999), Renaudeau et al (2003) e Moreira (2003) verificaram que porcas mantidas em ambiente com alta temperatura apresentaram maior número de movimentos respiratórios. O resfriamento do piso teve efeito (P<0,01), também, sobre a temperatura retal no período da manhã.…”

“…A exposição continuada de fêmeas lactantes a ambientes termicamente inadequados pode afetar a produção de leite e o comportamento estral, que ocasionam redução na taxa de concepção e aumento da mortalidade embrionária (Renaudeau et al, 2003). Uma alternativa para reduzir os efeitos negativos das altas temperaturas no desempenho de porcas na maternidade seria o resfriamento do piso no espaço destinado apenas à fêmea, aumentando a possibilidade de troca de calor e promovendo o conforto térmico para permitir à porca expressar seu potencial produtivo.…”