The Genetics of Thermoregulation in Pigs: A Review

Heat stress (HS) affects pig performance, health and welfare, resulting in a financial burden to the pig industry. Pigs have a limited number of functional sweat glands and their thermoregulatory mechanisms used to maintain body temperature, are challenged by HS to maintain body temperature. The genetic selection of genotypes tolerant to HS is a promising long-term (adaptation) option that could be combined with other measures at the production system level. This review summarizes the current knowledge on the genetics of thermoregulation in pigs. It also discusses the different phenotypes that can be used in genetic studies, as well as the variability in thermoregulation between pig breeds and the inheritance of traits related to thermoregulation. This review also considers on-going challenges to face for improving heat tolerance in pigs.

Comprehensive Evaluation of a Landscape Fabric Based Solar Air Heater in a Pig Nursery

Supplementing fossil fuels with solar air tempering for brooding young livestock could reduce energy use and improve indoor air quality. Metal transpired solar collectors (TSC) are effective but too expensive for heating livestock buildings. An inexpensive 12.7 m2 dark grey landscape-fabric-based transpired solar collector (fTSC) was evaluated in a swine nursery with two herds of pigs. A fraction of the fTSC area was underlain with phase change material (PCM) to store excess heat. The Test room with the fTSC was compared with an adjacent identical Control room, each with 120 piglets. The fTSC provided supplemental heating, e.g., with a suction velocity (Vs) of 0.027 m/s during a 9 h period, air temperature was increased by 11.6 °C (mean irradiance of 592 W/m2). Between 4 pm and 9 pm that same day, the PCM increased air temperature by 3.9 °C. The fTSC did not reduce propane use or improve pig performance. Higher Vs, operational changes and controller modifications could improve system performance and reduce cost. Modeling could be used to optimize PCM use. Hence, this very low-cost fabric-based solar air heater offers potential for considerable reduction in heat energy use in livestock barns.

PSIX-25 Feed and water deprivation at weaning and subsequent heat stress impacts serum and ileal markers of gastrointestinal integrity in nursery pigs

Social and environmental stressors impact nursery pig performance and may be linked to gastrointestinal dysfunction. The current experiment was conducted to investigate the impact of feed and water deprivation on serum stress markers and ileal mucosal gene expression in nursery pigs. Mixed-sex pigs were allotted on the basis of IBW (7.0 kg ± 0.89) in a RCBD with treatments in a split-plot arrangement and consisting of the whole-plot factor of with or without a 24-h feed and water deprivation at weaning and the sub-plot factor of with or without a cyclic 3-d heat stress starting 27 d post-weaning. On 1, 27, and 30 d post-weaning one pig from each pen was selected, blood was collected for measurement of serum cortisol, corticotrophin releasing factor (CRF), and endotoxins, and an ileal mucosal scraping was taken and gene expression of claudin 1 (CL-1), occludin (OC), and zonula occludens 1 (ZO-1) were measured by RT PCR. There was an increase (P < 0.05) in serum CRF and endotoxins and a tendency for an increase (P = 0.09) in serum cortisol due to the deprivation 1 d post-weaning. Further, there was a tendency for an increase (P < 0.10) in serum endotoxins and CRF due to the deprivation at 27 and 30 d post-weaning, respectively. Gene expression of CL-1 tended to increase (P = 0.10), and OC decreased (P = 0.05) due to the deprivation 1 d post-weaning. Expression of the OC gene decreased (P < 0.05) due to the deprivation 27 d post-weaning and OC and ZO-1 gene expression tended to decrease (P = 0.07) due to the heat stress 30 d post-weaning. These results show that post-weaning stress events alter serum stress markers and impact intestinal barrier function.

219 Effects of Feeding Low Protein Diets with Additional Supplementation of First Five Limiting AA on Performance and Diarrhea Incidence in Weaned Pigs

An experiment was conducted to evaluate the effect of feeding low crude protein (CP) diets and supplying 110% of the first 5 limiting AA on performance and diarrhea incidence in weaned pigs. One of 3 treatments were randomly assigned to 81 piglets (BW: 8.2 ± 1.2 kg; 9 pens/treatment; 3 pigs/pen) during 2 phases (3 wk each): a high CP (HP; 21 and 18%), a low CP (LP; 18 and 15%), or a low CP at 110% Lys, Met, Trp, Thr, Val requirements (LPAA; 18 and 15%) diet for phase 1 and 2, respectively. Pigs had ad libitum access to feed and water. Data were analyzed using PROC MIXED of SAS. During phase 1, pigs fed HP had the greatest ADG (P < 0.05), but ADFI and G:F were not different among treatments. In phase 2, no effect of treatments was observed on growth performance. Overall, pigs fed LPAA had the lowest (P < 0.05) ADG and G:F, and feeding LP decreased (P < 0.05) G:F. The ADFI was not affected by the treatments. Only during wk 3, pigs fed LPAA increased (P < 0.05) and LP tended to increase (P < 0.10) frequency of diarrhea compared to HP. On d 21, no treatment effect was observed for ileal villi height, but LPAA reduced (P < 0.05) and LP tended to reduce (P < 0.10) crypt depth compared to HP. Diet analysis revealed that LP was deficient in Ile and non-essential AA (NEAA), and LPAA contained inadequate levels of Ile, Leu, His and NEAA, which explains why reduced pig performance was achieved with these 2 diets. In conclusion, low CP diets, even with additional supplementation of the first 5 limiting AA, if deficient in the next limiting AA, results in negative effects on performance and diarrhea incidence.

Reproductive performance of indigenous Lao pigs reared by small-scale farmers in northern provinces of Laos

Indigenous pigs are essential domestic animals for rural life and meat supply in Laos, especially for ethnic people in remote areas. Northern provinces have the most numerous indigenous pig populations, i.e. covering 84 % of the total pig population. This study was conducted in northern Laos, where 164 pig-raising households, 325 sows and 1246 piglets were included. The study aimed to observe the general trend of change in indigenous pig utilization and the altered reproductive performance regarding village location and rearing systems. The semi-structured questionnaires were a key tool for gathering data required through personal interviews and field observations. Two types of indigenous Lao pig breeds (locally named Moo Lath and Moo Hmong) were found in study areas. The village locations were not influencing on reproductive performance of indigenous Lao pigs. Larger litter size and birth weight (P<0.004–0.000) was found in the second cluster (15 to 30 km away from downtown) with an average of 8.24 heads and 0.88 kg, while the first (<15 km) and third (>30 km) clusters had 7.72 versus 7.12 heads, and 0.70 versus 0.63 kg, respectively. Conversely, the second cluster had lower litter per year (P<0.001) by 1.04, compared to 1.38 for the first and third clusters. The free-scavenging rearing system (FRS) had a higher litter size (8.5) than the confinement (CRS) and semi-scavenge (SRS) rearing system (7.36 versus 7.54). The FRS had a marginally smaller litter per year (0.87) that differed from the CRS and SRS (1.45 and 1.41). The CRS had a shorter suckling period (2.38 months) with a lower weaning weight (6.74 kg), while the FRS and SRS had longer (2.72 versus 2.8 months) and higher weaning weight (7.76 and 7.57 kg). The mortality before weaning was 15 %, and no difference was found related to the villages' location or rearing systems (P>0.070 versus 0.839). Around 56 % of the piglet's deaths were due to poor management that caused piglets to be crushed/injured by sow or starvation. More than 54 % of farmers did not keep sows in pens before the farrowing, and 53 % of sows gave birth near forests. In conclusion, the village locations and rearing systems did not influence the reproductive performance of indigenous pigs in northern Laos. However, pre- and post-farrowing management had a strong effect on it. During the whole study, we took into consideration the successful example of Hungarian Mangalica pig, which could find a proper new role in the global premium markets. Our results suggest that similar complex semi-intensive farm operations as indigenous Mangalica pig farms in Hungary should be a great option for introducing and adapting to improve indigenous pig performance in Laos.

The effects of pharmacological levels of zinc, diet acidification and dietary crude protein on growth performance on nursery pigs

This experiment was conducted to evaluate potential replacements for pharmacological levels of Zn (provided by Zn oxide), such as diet acidification (sodium diformate), and low dietary crude protein (CP: 21 vs 18%) on nursery pig performance and fecal dry matter (DM). A total of 360 weaned pigs (Line 200 × 400, DNA, Columbus, NE; initially 5.90 ± 0.014 kg) were used in a 42-d growth study. Pigs were weaned at approximately 21-d of age and randomly assigned to pens (5 pigs per pen). Pens were then allotted to 1 of 8 dietary treatments with 9 pens per treatment. Experimental diets were fed in two phases: Phase 1 from weaning to d 7 and phase 2 from d 7 to 21; with all pigs fed the same common diet from d 21 to 42. The eight treatment diets were arranged as a 2 × 2 × 2 factorial with main effects of Zn (110 mg/kg from d 0 to 21 or 3,000 mg/kg from d 0 to 7, and 2,000 mg/kg from d 7 to 21), diet acidification, (without or with 1.2% sodium diformate), and dietary CP (21 or 18%, 1.40 and 1.35% in Phase 1 and 2 vs 1.20% standardized ileal digestible Lys, respectively). Fecal samples were collected weekly from the same 3 pigs per pen to determine DM content. No 2- or 3-way interactions (P &gt; 0.05) were observed throughout the 42-d study for growth performance; however, there was a Zn × acidifier × CP interaction (P &lt; 0.05) for fecal DM on d 7 and for the overall average of the 6 collection periods. Reducing CP without acidification or pharmacological levels of Zn increased fecal DM, but CP had little effect when ZnO was present in the diet. From d 0 to 21, significant (P &lt; 0.05) main effects were observed where average daily gain (ADG) and gain:feed (G:F) increased for pigs fed pharmacological levels of Zn, sodium diformate, or 21% CP (P &lt; 0.065). In the subsequent period (d 21 to 42) after the experimental diets were fed, there was no evidence of difference in growth performance among treatments. Overall (d 0 to 42), main effect tendencies were observed (P &lt; 0.066) for pigs fed added Zn or sodium diformate from d 0 to 21 whereas pigs fed 21% CP had greater G:F than those fed 18% CP. Pig weight on d 42 was increased by adding Zn (P &lt; 0.05) or acidifier (P &lt; 0.06) but not CP. In summary, none of the feed additives had a major influence on fecal DM, but dietary addition of pharmacological levels of Zn or sodium diformate independently improved nursery pig performance.

Effect of a carbohydrase admixture in growing pigs fed wheat-based diets in thermoneutral and heat stress conditions

The efficacy of exogenous carbohydrases in pig diets has been suggested to depend on enzyme activity and dietary fiber composition, but recent evidence suggests other factors such as ambient temperature might be important as well. Therefore, we investigated the effect of heat stress (HS) on the efficacy of a multienzyme carbohydrase blend in growing pigs. Ninety-six (barrows: gilts; 1:1) growing pigs with initial body weight (BW) of 20.15 ± 0.18 kg were randomly assigned to six treatments, with eight replicates of two pigs per pen in a 3 × 2 factorial arrangement: three levels of carbohydrase (0, 1X, or 2X) at two environmental temperatures (20 °C or cyclical 28 °C nighttime and 35 °C day time). The 1X dose (50 g/tonne) provided 1,250 viscosimetry unit (visco-units) endo-β-1,4-xylanase, 4,600 units α-l-arabinofuranosidase and 860 visco-units endo-1,3(4)-β-glucanase per kilogram of feed. Pigs were fed ad libitum for 28 d and 1 pig per pen was sacrificed on day 28. There was no enzyme × temperature interaction on any response criteria; thus, only main effects are reported. Enzyme treatment quadratically increased (P &lt; 0.05) BW on day 28, average daily gain (ADG) (P &lt; 0.05), and average daily feed intake (ADFI) (P &lt; 0.05) with the 1X level being highest. HS reduced the BW at day 14 (P &lt; 0.01) and day 28 (P &lt; 0.01), ADG (P &lt; 0.01), and ADFI (P&lt;0.001). There was a trend of increased feed efficiency (G:F) (P &lt; 0.1) in the HS pigs. HS increased apparent jejunal digestibility of energy (P &lt; 0.05) and apparent ileal digestibility of calcium (P &lt; 0.01). At day 1, HS reduced serum glucose (P &lt; 0.001) but increased nonesterified fatty acid (P &lt; 0.01). In the jejunum, there was a trend of increased villi height by carbohydrases (P &lt; 0.1), whereas HS reduced villi height (P &lt; 0.05). HS increased the jejunal mRNA abundance of IL1β in the jejunum (P &lt; 0.001). There was a trend for a reduction in ileal MUC2 (P &lt; 0.1) and occludin (P &lt; 0.1) by HS, and a trend for increased PEPT1 (P &lt; 0.1). There was no effect of HS on alpha diversity and beta diversity of the fecal microbiome, but there was an increase in the abundance of pathogenic bacteria in the HS group. In conclusion, HS did not alter the efficacy of carbohydrases. This suggests that carbohydrases and HS modulate pig performance independently.

The influence of particle size of Enogen Feed corn and conventional yellow dent corn on nursery and finishing pig performance, carcass characteristics and stomach morphology

Enogen Feed corn is a variety developed by Syngenta Seeds (Downers Grove, IL) that has been genetically modified to contain an α-amylase enzyme trait (SYT-EFC). Originally, Enogen feed corn was developed for the ethanol industry due to its reduction in viscosity of the corn mash, thus eliminating the need to add a liquid form of the α-amylase enzyme. However, there is potential application for Enogen Feed corn to be used in livestock diets due to the increase in α-amylase enzyme potential to increase starch digestibility. A more common method of increasing starch digestibility in corn is to finely grind it to reduce particle size. This increases the surface area and allows for greater interaction with digestive enzymes. We hypothesized that pigs fed Enogen feed corn potentially could achieve similar gain:feed ratio (G:F) at larger particle sizes than conventional corn because of the differences in starch digestibility. In Exp. 1, a total of 360 pigs (DNA 200 × 400, Columbus, NE; initially 6.6 ± 0.1 kg BW) were used with 5 pigs per pen and 12 pens per treatment. Treatments were arranged in a 2 × 3 factorial with main effects of corn source (Enogen Feed corn or conventional yellow dent corn) and ground corn particle size (300, 600, or 900 µm). Overall, there was a corn source × particle size interaction (linear, P = 0.027) for G:F. There was no effect due to particle size when pigs were fed conventional yellow dent corn, but in pigs fed Enogen Feed corn, G:F increased with decreasing particle size. Neither corn source nor particle size affected (P &gt; 0.05) overall average daily gain (ADG) or average daily feed intake (ADFI). In Exp. 2, a total of 323 pigs (241 × 600; DNA, Columbus, NE; initially 50.0 ± 1.3 kg) were used with 9 pigs per pen and 6 pens per treatment. Treatments were identical as Exp. 1. Overall, corn source had no effect on finishing pig ADG, ADFI or G:F. For corn particle size, ADG and G:F increased (linear, P &lt; 0.014) and ADFI decreased (P = 0.043) as particle size decreased. For stomach morphology, there was a tendency for a corn source × particle size interaction (P = 0.055) for keratinization score with keratinization increasing linearly (P = 0.001) as particle size of the corn decreased for yellow dent corn with no change in keratinization score as particle size decreased for Enogen Feed corn. In summary, reducing corn particle size improved G:F with no major differences observed between corn sources for overall pig performance.

Influence of Enogen Feed corn and conventional yellow dent corn in pelleted or meal-based diets on finishing pig performance and carcass characteristics

Genetic modification of corn has enhanced the use of different corn hybrids in animal agriculture. Enogen Feed corn, developed by Syngenta Seeds (Downers Grove, IL), has potential for use in livestock diets due to increase α-amylase enzyme in the corn thus improving starch digestibility. In addition, the pelleting process also increases starch gelatinization which increases its digestibility by the pig, increasing growth rate and improving feed efficiency. Therefore, pelleting Enogen Feed corn might prove to provide a greater response in growth performance than conventional yellow dent corn. Thus, the objective of this experiment was to determine the effects of corn source and diet form on growth performance and carcass characteristics of finishing pigs. A total of 288 pigs (53.0 ± 0.5 kg) were used with 8 pigs per pen and 9 pens per treatment in a 72-d study. Treatments were arranged in a 2 × 2 factorial with main effects of corn source (Enogen Feed corn or conventional yellow dent corn) and diet form (meal or pellet). For overall (d 0 to 72) performance, no interactions between corn source and diet form were observed. There was a tendency (P &lt; 0.10) for slightly improved average daily gain (ADG) and gain:feed ratio (G:F) for pigs fed conventional yellow dent corn compared to those fed Enogen Feed corn. For feed form, pigs fed pelleted diets had increased (P &lt; 0.001) ADG and G:F compared to pigs fed meal diets. For carcass characteristics, pigs fed pelleted diets had increased hot carcass weight compared to pigs fed meal diets (P &lt; 0.001). In summary, feeding pelleted diets to finishing pigs increased ADG and improved feed efficiency compared to those fed meal-based diets. There were no major differences between observed corn sources or interactions between corn source and diet form on growth performance.

Research Progress on Oxidative Stress and Its Nutritional Regulation Strategies in Pigs

Oxidative stress refers to the dramatic increase in the production of free radicals in human and animal bodies or the decrease in the ability to scavenging free radicals, thus breaking the antioxidation–oxidation balance. Various factors can induce oxidative stress in pig production. Oxidative stress has an important effect on pig performance and healthy growth, and has become one of the important factors restricting pig production. Based on the overview of the generation of oxidative stress, its effects on pigs, and signal transduction pathways, this paper discussed the nutritional measures to alleviate oxidative stress in pigs, in order to provide ideas for the nutritional research of anti-oxidative stress in pigs.