Evaluation and mitigation of the effects of in utero heat stress on piglet growth performance, postabsorptive metabolism, and stress response following weaning and transport

Abstract

In utero heat stress (IUHS) increases energy requirements of pigs during postnatal life, and this may compound weaning and transport stress. The study objective was to evaluate and mitigate the negative effects of IUHS following weaning and transport through the provision of a nutrient dense (ND) nursery diet formulated to meet the greater energy requirements of IUHS pigs during the first 14 d post-weaning and transport. Twenty-four pregnant gilts were exposed to thermoneutral (TN; n = 12; 17.5 ± 2.1°C) or heat stress (HS; n = 12; cycling 26°C to 36°C) conditions for the first half of gestation (d 6 to 59) and then TN conditions (20.9 ± 2.3°C) until farrowing. Nine TN gilts and 12 HS gilts produced litters. At weaning (16.2 ± 0.4 d), mixed-sex piglets (N = 160; 4.78 ± 0.15 kg BW) were transported (loading + transport + unloading) for 11 h 40 min. Following transport, piglets were blocked into pens (n = 4 pigs/pen) by in utero and dietary treatments: in utero thermoneutral (IUTN) + control diet (C; n = 10 pens), IUTN + ND (n = 10 pens), IUHS + C (n = 10 pens), IUHS + ND (n = 10 pens). Treatment diets were fed from d 1 to 14 post-weaning and transport (Period 1), and the C diet was fed to all pigs from d 14 to 35 post-weaning and transport (Period 2). Production measures were taken in 7 d intervals to calculate average daily gain (ADG), average daily feed intake (ADFI), average daily net energy intake (ADEI), gain:feed, and gain: net energy intake. Blood samples were collected prior to transport (Pre-T), following transport (Post-T), and on d 2, 7, 14, 28, and 35 post-weaning and transport to analyze cortisol, glucose, insulin, and non-esterified fatty acids (NEFA). Behavior was assessed through video-recording on d 3, 5, 8, 11, and 13 post-weaning and transport. In Period 1, ADG was reduced (P = 0.04; 20.0 g/d) in IUHS vs. IUTN pigs. Pigs fed ND diets had reduced ADFI (P = 0.02; 9.3%) compared to C diet fed pigs during Period 1, which resulted in similar ADEI (P = 0.23; 1,115 ± 35 kcal/d). During transport, cortisol was decreased (P = 0.03; 25.8%) in IUHS vs. IUTN pigs. On d 2, glucose was decreased (P = 0.01; 13.8%) in IUHS vs. IUTN pigs. No in utero treatment-related behavior differences were observed but lying was reduced (P = 0.03; 6.5%) and standing was increased (P = 0.04; 14.1%) in ND vs. C pigs overall. In summary, IUHS reduced growth performance in pigs following weaning and transport and providing a ND diet did not rescue the lost performance.

Effects of cooling systems on physiological responses and intestinal microflora in early gestating sows exposed to high-temperature stress

“…Increased temperatures and heat waves due to the changing climate have negatively affected the animal industry [ 1 , 2 ]. In such conditions, livestock can suffer heat stress (HS) that may severely reduce carcass quality via reduced lean growth and increased fat content [ 3 , 4 ]. The HS reduces the growth rate of livestock by lowering feed intake and it causes an imbalance in physiological responses such as blood metabolic indicators, respiration rate, nutrient metabolism, and rectal temperature [ 5 ].…”

Impacts of in Utero Heat Stress on Carcass and Meat Quality Traits of Market Weight Gilts

“…Numerous factors are known to contribute to the color of fresh meat products including chronic and acute stress pre-slaughter, glycolytic potential, genetics, among others [ 46 ]. As previously mentioned, IUHS has been associated with energy metabolism [ 4 , 9 , 10 ] and the stress response [ 9 , 11 , 12 ] in swine. However, it appeared such differences did not have any meaningful effect on oxidative stability shown by instrumental display color and TBARS values, nor on the extent of protein denaturation shown by transmission values.…”

“…The present study was conducted in parallel with Maskal et al [ 10 ], and detailed treatment information regarding live animals can be found there. Briefly, dams utilized in the study were first parity F1 Landrace × Large White gilts ( n = 24) sired by a single Duroc line (Choice Genetics USA, Des Moines, IA, USA).…”

“…Following transport, piglets were housed in groups in 40 mixed sex pens ( n = 4/pen), and the remaining 73 piglets were not utilized for the study. Pigs utilized for this study were fed the nutrient dense diet for the first 14 d following transport as described by Maskal et al [ 10 ], and all animals were raised under thermoneutral conditions regardless of IUHS environment.…”

“…Differences in performance and carcass composition through IUHS are often attributed to differential energy metabolism, as several studies have observed changes in blood insulin levels and glucose metabolism [ 4 , 9 , 10 ]. Similarly, offspring exposed to IUHS often exhibit increased blood cortisol [ 11 , 12 ], although decreased blood cortisol was observed by Byrd et al [ 9 ] and Maskal et al [ 10 ] following prolonged stress exposure. The level of blood cortisol has been shown to be related to multiple carcass quality attributes such as a positive correlation to carcass weight and backfat thickness and a negative correlation to lean carcass content [ 13 ].…”