A meta-analysis of the effects of high ambient temperature on growth performance of growing-finishing pigs

High ambient temperature (T) is one of the most important climatic factors influencing pig performance. Increased T occurs sporadically during summer heat waves in temperate climates and year round in tropical climates. Results of published experiments assessing the effects of high T on pig performance are surprisingly variable. Thus, a meta-analysis was performed to aggregate our knowledge and attempt to explain differences in the results across studies on the effect of increased T on ADFI and ADG in growing-finishing pigs. Data for ADFI and ADG were extracted from 86 and 80 trials, respectively, from articles published in scientific journals indexed in PubMed, Science Direct, and from proceedings of scientific meetings through November 2009. Data on ADFI and ADG were analyzed using a linear mixed model that included the linear and the quadratic effects of T and BW, and their interactions as continuous, fixed effects variables, and the trial as a random effect factor (i.e., block). In addition, the effects of housing type (2 levels: individual and group housing) and the year of publication (3 levels: 1970 to 1989, 1990 to 1999, and 2000 to 2009) on the intercept and the linear regression term for T (i.e., the slope) were also tested. Results showed that high T had a curvilinear effect on ADFI and ADG and that this effect was more pronounced in heavier pigs. Across T, ADFI was less when pigs were group-housed. The intercept and the regression coefficient (slope) for T were significantly affected by the year of publication. The effect of increased T was greater in more contemporary works, suggesting that modern genotypes could be more sensitive to heat stress than older genotypes of lesser growth potential. In conclusion, pig performance decreases at an accelerating rate as T is increased. The large between-study variability on the effects of high T on pig performance is partially explained by differences in pig BW and to a lesser extent by the year the study was published.     

Effect of ambient temperature on mammary gland metabolism in lactating sows

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.     

季节对民猪CSDE1表达的影响及其分子调节网络

民猪是具有抗寒特性的地方猪种,研究民猪对环境温度的适应机制对于理解其抗寒特性具有重要意义。本试验通过检测4个季节民猪外周血单核细胞中含CSD结构域的E1蛋白(cold shock domain-containing protein E1,CSDE1)、miR-1和miR-331-3p表达情况,并通过在PK15细胞中过表达CSDE1基因,检测细胞中7种干扰小RNA和8种基因,研究CSDE1在民猪环境温度适应中的作用和分子调控网络。结果表明,CSDE1在春、秋季表达量较低,而在夏、冬季表达量较高,而RNA miR-1和miR-133-3p的表达规律则相反;过表达CSDE1后细胞中小RNA miR-1、miR-101、miR-1307和基因HDAC3、BTF3、HSF2、TCEA1 mRNA的相对表达量明显上升,miR-143-3p和CHD7mRNA的相对表达量明显下降,各试验组差异显著(P<0.05)。结果表明,CSDE1的表达受到民猪所处环境温度的影响,可以被干扰小RNA调节,并进一步影响其他基因的表达。     

Acclimation to high ambient temperature in Large White and Caribbean Creole growing pigs

The effect of breed [Creole (CR) vs. Large White (LW)] on performance and physiological responses during acclimation to high ambient temperature was studied in 2 experiments involving 24 (12/breed) growing pigs each. Pigs were exposed to 24 degrees C for 10 d (d -10 to -1) and thereafter to a constant temperature of 31 degrees C for 16 d (d 1 to d 16) in Exp. 1 and for 20 d (d 1 to d 20) in Exp. 2. For both experiments, the temperature change was achieved over 4 h on d 0. The first experiment began at 105 d of age, and the average BW of CR and LW pigs was 36.6 +/- 2.5 kg and 51.7 +/- 3.0 kg, respectively. The second experiment was designed to compare both breeds at a similar BW (about 52 kg on d 0). Pigs were individually housed and given ad libitum access to feed. At 24 degrees C, ADG was lower (P < 0.01) in CR than in LW (602 vs. 913 g/d and 605 vs. 862 g/d in Exp. 1 and 2, respectively), but the ADFI was not affected by breed (190 and 221 g x d(-1) x kg(-0.60) in Exp. 1 and 2, respectively). Short-term thermoregulatory responses during the 4-h transition from 24 to 31 degrees C (d 0) were analyzed according to a linear plateau model to determine the break point temperature, above which rectal temperature (RT), cutaneous temperature (CT), and respiratory rate (RR) began to change. The CT increased linearly with temperature increase (0.22 degrees C/ degrees C) and was less (P < 0.05) in CR than in LW (by -0.3 degrees C on average). In both experiments, the break point temperature for RT was not affected by breed (27.6 degrees C on average), whereas for RR it was greater (P < 0.05) in CR than in LW (27.5 vs. 25.5 degrees C, P < 0.01). On average, ADFI declined by about 50 g x d(-1) x kg(-0.60) from d -1 to d 1 (P < 0.01), and thereafter at 31 degrees C, it gradually increased (23 g x d(-1) x kg(-0.60); P < 0.05), suggesting an acclimation to high exposure. This response was not influenced by breed. After the day that marked the beginning of the acclimation response (i.e., the threshold day), RR, CT, and RT declined over the duration of exposure to 31 degrees C (P < 0.05) in both experiments. During this period, RT and CT were less in CR than in LW pigs (39.6 vs. 39.9 degrees C and 37.9 vs. 38.2 degrees C, respectively; P < 0.05), whereas RR was not affected by breed. The threshold day at which RT began to decline was less in CR than in LW pigs (0.18 vs. 1.17 d and 0.39 vs. 0.93 d in Exp. 1 and 2, respectively; P < 0.05). In conclusion, this study suggests that short- and long-term physiological reactions during heat acclimation differed when CR and LW pigs were compared at the same age or BW.     

淀山湖水葫芦用于饲喂生长育肥猪的效果研究

水葫芦干粉的加工工艺：打捞→冲洗→挤压／粉碎→瞬间烘干→装袋贮存→配制饲料     

Influence of a high ambient temperature on lipid metabolism in the growing pig

Because pigs are fatter when they are heat-stressed, it was hypothesized that lipid metabolism is enhanced in heat-stressed pigs. To test this hypothesis, an experiment was conducted to determine the influence of a high ambient temperature on the level of plasma lipids, thyroid hormones, lipoprotein lipase activity, and on the composition of very low density lipoproteins (VLDL) and chylomicrons in the growing pig. Twelve Large White x Landrace castrated male pigs with an initial weight of 20 +/- 0.6 kg were allotted to one of the following treatments: 1) ambient temperature of 31 degrees C, with ad libitum access to feed or 2) ambient temperature of 20 degrees C and fed the amount consumed by those kept at 31 degrees C until 35 kg BW. Ambient temperature did not affect piglet performance. Compared to that in pigs kept at 20 degrees C, in pigs kept at 31 degrees C the lipid content of backfat was 26% higher and the proportion of flare fat was increased by more than twofold (P < 0.001). Lipoprotein lipase activity was increased more than twofold in backfat and nearly twofold in leaf fat at 31 vs 20 degrees C (P < 0.001). In warmth-exposed (31 degrees C), feed-restricted pigs, the plasma level of triiodothyronine was 30% lower than at 20 degrees C (P < 0.001), whereas VLDL-lipid concentration was more than fourfold higher, and plasma concentrations of NEFA and triglycerides were 2.6- and 3.6-fold higher, respectively (P < 0.001). In conclusion, the chronic exposure of growing pigs to a high ambient temperature enhances lipid metabolism in both the liver (VLDL production) and the adipose tissue (lipoprotein lipase activity). Consequently, plasma triglyceride uptake and storage are facilitated in the adipose tissue, which results in greater fatness.     

Fluctuating ambient temperature for weaned pigs: effects on performance and immunological and endocrinological functions

Following weaning at 3 wk of age, crossbred barrows and gilts were housed in temperature-controlled rooms for a 5-d adjustment period at 35 degrees C, then assigned to receive constant ambient temperature (CT) or fluctuating ambient temperature (FT) treatment for the nursery phase of the experiment. Pigs in FT received 12 h at 35 degrees C and 12 h at 15 degrees C daily for the initial 2 wk of the experiment, then 12 h at 29 degrees C and 12 h at 9 degrees C daily for the final 2 wk. Pigs in CT received 35 degrees C and 29 degrees C continuously for the first and final 2 wk, respectively. Weekly growth performance, feed intake and feed-conversion efficiency were not affected by treatment. Plasma glucose, serum cortisol, monocyte phagocytic function and antibody response to a commercial E. coli bacterin were similar in pigs exposed to CT and FT treatments. Concentrations of insulin in serum were similar between treatments at 0, 1 and 3 wk but were increased for pigs in FT at 2 (P less than .05) and 4 wk (P less than .01). Numbers of lymphocytes, band neutrophils and monocytes in pigs were not influenced by ambient temperature treatment. However, numbers of mature neutrophils for pigs in FT were increased (P less than .05) at 1 and 3 wk of treatment. Eosinophils were also elevated in FT pigs at 4 wk of treatment. Pairs of littermate pigs that had been given CT and FT treatments were selected randomly to continue on the finishing phase of the experiment.(ABSTRACT TRUNCATED AT 250 WORDS)     

热带地区乳酸菌发酵饲料对育肥猪生产性能的影响

试验旨在研究添加不同比例乳酸菌发酵饲料对热带地区75～100 kg育肥猪生产性能的影响。选用体重约75 kg三元杂交(杜×长×大)猪416头,按性别和体重随机分为4组。对照组饲喂常规全价日粮,试验组乳酸菌发酵饲料占干粉料的比例设3个梯度:试验1组20%(以风干物质计,下同),试验2组30%,试验3组50%。结果表明:在平均舍内温度为30.4℃,平均相对湿度为76.2%的条件下,试验1、2、3组的平均日增重分别比对照组提高了1.16%、6.97%和11.63%;平均日采食量分别比对照组提高了1.03%、1.10%和2.66%,试验3组和对照组差异显著(P<0.05);平均料肉比分别比对照组降低了1.29%、6.43%和9.00%;分别比对照组多盈利2、19、29个百分点。在热带地区75～100 kg育肥猪日粮中添加50%的乳酸菌发酵饲料时能最大限度地提高生产性能和收益。     

Relationship between mean body surface temperature measured by use of infrared thermography and ambient temperature in clinically normal pigs and pigs inoculated with Actinobacillus pleuropneumoniae

OBJECTIVE: To determine the relationship between ambient temperature and mean body surface temperature (MBST) measured by use of infrared thermography (IRT) and to evaluate the ability of IRT to detect febrile responses in pigs following inoculation with Actinobacillus pleuropneumoniae. ANIMALS: 28 crossbred barrows. PROCEDURES: Pigs (n = 4) were subjected to ambient temperatures ranging from 10 to 32 C in an environmental chamber. Infrared thermographs were obtained, and regression analysis was used to determine the relationship between ambient temperature and MBST. The remaining pigs were assigned to groups in an unbalanced randomized complete block design (6 A pleuropneumoniae-inoculated febrile pigs [increase in rectal temperature > or = 1.67 C], 6 A pleuropneumoniae-inoculated nonfebrile pigs [increase in rectal temperature < 1.67 C], and 12 noninoculated pigs). Infrared thermographs and rectal temperatures were obtained for the period from 2 hours before to 18 hours after inoculation, and results were analyzed by use of repeated-measures ANOVA. RESULTS: A significant linear relationship was observed between ambient temperature and MBST (slope, 0.40 C). For inoculated febrile pigs, a treatment X method interaction was evident for rectal temperature and MBST, whereas inoculated nonfebrile pigs only had increased rectal temperatures, compared with noninoculated pigs. A method X time interaction resulted from the longer interval after inoculation until detection of an increase in MBST by use of IRT. CONCLUSIONS AND CLINICAL RELEVANCE: Infrared thermography can be adjusted to account for ambient temperature and used to detect changes in MBST and radiant heat production attributable to a febrile response in pigs.     

黑麦草饲喂肉猪效果试验

黑麦草属禾本科优质牧草，具有适应性强、产量高、适口性好、易于家畜消化等特点。其鲜草中含粗蛋白质３．５８％～３． ８８％；干物质 １６． ２％；赖氨酸０． ６１％，是发展草－畜配套型畜牧业的选用牧草之—。为了研究其喂猪最佳的比例、饲喂效果和经济效益，给推广黑麦草喂猪提供科学依据，特进行本次试验。１试验材料与方法１．１时间与地点试验在我市城富某养猪专业户中进行，预饲期７ｄ，正饲期由１９９９年９月１２日至１９９９年１２月１２日，试验期９０ｄ。１．２试验猪的选择与分组选择窝别、性别、体重基本一致的杜、长、太…     

The effect of rank order on feed intake and growth of fattening pigs

On the basis of 120 fattening pigs, classified in 6 groups of 20 animals each, the rank order was determined and its influence on the feed intake behaviour as well as on the fattening progress was studied. The results show that with respect to the total length of stay at the trough and to the time per visit to the feeding station the dominant barrows stayed significantly longer at the feeding place than their subordinate pen mates. Additionally, they showed a higher weight at the end of the fattening period and a higher weight gain per day of fattening. As to the frequency of the visits to the feeding station there was no significant difference between high-ranking and low-ranking animals during the period of observation.     

高温胁迫对黑麦草生长及生理代谢的影响

以两个耐热性差异较大的多年生黑麦草品种首相(Premier,耐热性强)和顶峰(Pinnacle,耐热性弱)为试验材料,分析了人工模拟昼夜温度为适温(25 ℃/20 ℃)和高温(35 ℃/30 ℃)两种温度条件下,高温胁迫对黑麦草生长、叶片细胞膜稳定性、叶绿素含量、光合作用、内源激素(ABA、IAA,GA₃和ZR)以及碳水化合物(可溶性糖、淀粉、果聚糖)代谢的影响。结果表明,高温胁迫条件下黑麦草生长减缓,叶片电导率升高,叶绿素含量和光合作用显著下降,内源激素脱落酸(ABA)含量升高,而生长素(IAA)、赤霉素(GA₃)和细胞分裂素(ZR)含量均下降,但是在耐热性强的品种中的变化程度均小于耐热性弱的品种;高温胁迫下碳水化合物中的可溶性糖含量随处理时间的延长呈先升高随后下降的趋势,淀粉含量在两个品种中均呈不同程度的下降,果聚糖含量在耐热性强的品种中升高,在耐热性弱的品种中先升高随后下降。高温胁迫下黑麦草叶片中积累或维持较高的内源激素(ABA、GA₃、IAA、ZR)和碳水化合物(可溶性糖和果聚糖)可能是耐热性较强的主要原因,这些内源激素或碳水化合物的积累或维持有助于黑麦草细胞内渗透平衡和细胞膜稳定性,保护光合器官免受损害以维持光合能力,延缓因高温和呼吸增强导致的叶片的枯黄衰老,从而提高了黑麦草的耐高温能力。     

纱棘提取物对断奶仔猪生长和脂肪代谢的影响

试验选用(28±2)日龄东北民猪和"长×大"二元杂交断奶仔猪各24头,分别随机分为两个处理组,每组3个重复,每个重复4头猪(公母各半).试验组添加1 000 mg/kg沙棘提取物,研究沙棘提取物对断奶仔猪生产性能和脂肪代谢的影响.结果表明:①沙棘提取物对东北民猪和"长×大"猪平均日增重和料重比的影响不显著(P>0.05);②沙棘提取物提高了民猪试验组血清GH水平,降低了民猪试验组的血清TC、LDL、HDL含量和"长×大"猪血清INS水平.     

The effect of aflatoxins on growth in pigs and the biological value of the meat

Twelve pigs were subjected to model trials to study the effect of an aflatoxin-contaminated pig-fattening diet, administered for 26 days. Aflatoxin B1 constituted 55% of the aflatoxins tested. The aflatoxin concentrations used in the trials were 30 and 300 micrograms per 1 kg of feed. No clinical effect of aflatoxin was observed in the pigs. Aflatoxins were found to have adverse effects on proteosynthesis. A decrease in the weight gains of the pigs was accompanied by a decrease in the total plasma protein and, in the group with the higher aflatoxin dose (300 micrograms per 1 kg of feed), also by an increase in the total bilirubin concentration in the blood serum. Perilobular steatosis, dissociation of the liver trabeculae, and more pronounced activation of the reticuloendothelial system were demonstrated by the histological examination of liver tissue. An increase in the content of hydroxyproline was recorded in the muscle of the experimental pigs. It is documented by the results that the aflatoxin dose of 30 micrograms per 1 kg of feed (the recommended maximum admissible concentration for the Czech Socialist Republic) is high enough to reduce the performance of pigs and the biological value of their meat.     

Effects of ambient temperature and restricted feeding on the growth of feathers in growing turkeys

1. Male turkeys were reared to 6 weeks of age at 15 degrees C and 26 degrees C and fed ad libitum or restricted to 0.5 of the body weight of birds fed ad libitum. Basal metabolic rate was determined by indirect calorimetry at an ambient temperature of 20 degrees C. 2. Turkeys at 15 degrees C were lighter than those kept at 26 degrees C. Feather lengths and weight were similar in both groups. Fasting heat production corrected for both metabolic body size and activity was greater in turkeys reared at 15 degrees C than those at 26 degrees C. 3. Cranial breast feathers were significantly longer in restricted birds than in those fed ad libitum in contrast to a proportional decrease in the lengths of other feathers of 0.1 to 0.3. Feather weight as a proportion of body weight was 0.072 in restricted turkeys compared with 0.046 in birds fed ad libitum. There was no difference in basal metabolic rate between ad libitum and restricted turkeys. 4. It was concluded that feather growth was maintained in preference to body and muscle growth and that rearing birds at 15 degrees C did not improve breast feather cover. It is suggested that the growth of breast feathers in turkeys fed ad libitum is impaired.     

Physiological responses to treadmill exercise and ambient temperature in normal and malignant hyperthermia susceptible pigs.

Ten susceptible and ten resistant pigs to malignant hyperthermia were used to observe the effects of exercise and ambient temperature on selected physiological parameters. Pigs were submitted to a ten minute exercise on a treadmill operating at a speed of 1.8 km/h and inclined to 11 degrees. Exercise in the first group was at an ambient temperature of 14 degrees C, and in the second at 29 degrees C. The right carotid artery was previously cannulated for blood pressure measurements and for repeated blood sampling during exercise. Arterial pressure, heart rate, rectal and cutaneous temperatures were recorded. Levels of cortisol, creatine kinase and its isoenzymes were measured. At 14 degrees C, exercise caused some physiological adjustments in susceptible animals; heart rate, skin temperature and cortisol levels increased (P less than 0.05). In resistant pigs, only the heart rate was elevated significantly following exertional stress at 14 degrees C. Exercise at 29 degrees C produced severe stress and marked physiological changes: heart rate, rectal and skin temperatures and cortisol levels increased significantly in both susceptible and resistant swine. At 29 degrees C, susceptible pigs also had higher levels of serum cortisol, total creatine kinase and MM isoenzyme (P less than 0.05) compared to resistant pigs. The results indicate that, following exertional or thermal stress, susceptible pigs undergo more extensive physiological changes than do resistant pigs. Similar levels of stress prior to slaughter may trigger physiological changes which in the susceptible pigs would likely result in pale, soft exudative myopathy.