Increasing energy and lysine in diets for growing-finishing pigs in hot environmental conditions: consequences on performance, digestibility, slurry composition, and gas emission

The influence of dietary nutrient concentration on growth performance, manure composition, and gas emission was studied in pigs in hot environmental conditions. A total of 64 intact males and 64 females [(Landrace × Large White) × Pietrain] weighing 63.1 ± 9.7 kg were divided into 2 dietary treatments: high (HD: 14.39 MJ of DE/kg and 1.11% Lys) and low (LD: 13.97 MJ of DE/kg and 1.01% Lys) in energy and Lys contents. Pigs were allocated to 32 split-sex pens with 4 pigs/pen and 16 pens/treatment. Average productive performance was recorded for 41 d (phase 1). After phase 1, 12 females of 103.3 ± 3.15 kg (6 per treatment) were selected and housed individually, and feces and slurry were collected during 3 and 4 consecutive days, respectively, to calculate nutrient digestibility and measure gas emissions (phase 2). For gas emission measurements, slurry was pooled by treatment and stored for 76 d. Initial composition of slurry and pH were analyzed. Maximum and minimum temperatures registered in the barn throughout the growing period were 35.1 and 18.1°C, respectively. Animals fed the HD diet grew more efficiently than pigs fed the LD diet (G:F, 0.43 vs. 0.40; SEM = 0.01; P < 0.05). Fat digestibility was greater in HD compared with LD pigs (88.0 vs. 84.9%; SEM = 0.9; P < 0.05). Slurry from pigs fed the LD diet showed greater DM, OM, total N, and VFA contents than slurry from pigs fed the HD diet. Cumulative NH(3), CO(2), and especially CH(4) emissions were greater in the HD slurry compared with the LD slurry (192.4 vs. 210.g of NH(3)/m(3); 2,712 vs. 3,210 g of CO(2)/m(3); 1,502 vs. 2,647 mL of CH(4)/kg of OM). Increasing feed density in the present study led to a more efficient growth, a decreased nutrient concentration in the slurry, and a greater gas emission.     

饲养密度和硫辛酸对肉鸡血清指标、行为及骨骼发育的影响

本试验旨在研究高饲养密度条件下饲粮中添加硫辛酸(LA)对肉鸡血清指标、行为及骨骼发育的影响。试验选取健康状况良好、体重相近的1530只21日龄爱拔益加(AA)肉鸡,随机分成3组,即常规饲养密度组(ND组,15只/m^2,饲喂基础饲粮)、高饲养密度组(HD组,18只/m^2,饲喂基础饲粮)和高饲养密度+LA组(HD+LA组,18只/m^2,在基础饲粮在添加300 mg/kg LA),每组6个重复。试验期为3周。结果表明:1)与ND组相比,HD组肉鸡血清钙含量和碱性磷酸酶(ALP)活性显著下降(P<0.05),血清皮质酮(CORT)含量以及还原型辅酶Ⅱ氧化酶(NOX)和髓过氧化物酶(MPO)活性显著上升(P<0.05)。2)与ND组相比,HD组肉鸡行走、梳翅、采食频次与时间占比显著降低(P<0.05),而饮水频次以及饮水和趴卧时间占比显著升高(P<0.05)。3)与ND组相比,高饲养密度显著降低肉鸡胫骨与股骨直径、重量、密度、强度以及钙、磷、灰分和矿物盐含量(P<0.05)。4)与HD组相比,HD+LA组肉鸡血清钙含量和ALP活性显著升高(P<0.05),血清CORT含量以及NOX和MPO活性显著下降(P<0.05);采食频次和时间占比显著增加(P<0.05),饮水频次和趴卧时间占比显著降低(P<0.05);胫骨质量以及钙、磷含量与股骨密度、强度和钙含量显著上升(P<0.05)。综上所述,高饲养密度致使肉鸡发生氧化应激,改变了肉鸡行为,并使肉鸡骨骼质量下降,而饲粮中添加LA能在一定程度上缓解高饲养密度对肉鸡造成的损伤。     

The effects of thermal environment and spray-dried plasma on the acute-phase response of pigs challenged with lipopolysaccharide

Forty barrows (TR4 x C22) were weaned at 17 d of age (BW = 6.27 +/- 0.30 kg), housed (two pigs/pen) in a thermal-neutral environment (TN; constant 26.7 degrees C), and fed diets with or without 7% (as-fed basis) spray-dried plasma (SDP). On d 7, one pig/ pen was moved into a cold environment (CE; constant 15.6 degrees C). Pigs were fitted with jugular catheters on d 11. On d 12, 16 pigs per environment (eight pigs per dietary treatment) were challenged i.v. with 75 microg of lipopolysaccharide (LPS)/kg of BW. Blood samples were collected over a 4.5-h period. Pigs were then killed and tissue samples were harvested for messenger RNA (mRNA) analysis. From d 0 to 7, pigs fed SDP diets had a lower gain:feed ratio (G/F) than pigs fed no SDP (533 +/- 14 vs. 585 +/- 17 g/kg; P < 0.03). Pigs housed in the CE consumed more feed and had a lower G/F than pigs housed in TN from d 7 to 11 (P < 0.001). There were no environment x diet interactions from d 7 to 11 (P > 0.78). Baseline concentrations of serum ACTH and cortisol were lower in the TN pigs than in the CE pigs (P < 0.001). Pigs fed diets without SDP had lower serum cortisol concentrations over the 4.5-h period than pigs fed SDP (time x diet, P < 0.001). Serum concentrations of tumor necrosis factor-alpha (TNF-alpha) were highest for pigs consuming SDP in the CE, whereas there were no differences among the other treatments (time x diet x environment, P < 0.02). Pigs housed in the CE had higher serum interleukin-1beta (IL-1beta) (P < 0.001) and interleukin-6 (IL-6; P < 0.001) than TN pigs. Pigs fed SDP also had slightly higher serum IL-1beta concentrations (P < 0.10) and higher (P < 0.001) IL-6 concentrations than pigs fed no SDP. Pigs fed SDP had 9% lower liver and 13% lower thymus mRNA expression of tumor necrosis factor-alpha (TNF-alpha) than pigs that consumed no SDP (P < 0.06). Liver IL-1beta, IL-6, and LPS-binding protein mRNA were higher in the CE than in the TN (P < 0.03, P < 0.001, and P < 0.05; respectively). In addition, spleen TNF-alpha (P < 0.03) and IL-6 (P < 0.01) mRNA levels were higher in the CE than in the TN. Pigs consuming SDP and challenged with LPS responded with elevated serum concentrations of cortisol and cytokines compared with pigs fed diets with no SDP. Housing pigs in a CE increased the baseline concentrations of ACTH and cortisol, and when coupled with an LPS challenge, resulted in elevated serum and tissue mRNA levels of cytokines. Cold stress and feeding SDP during a LPS challenge may result in increased stress and immune responses in young pigs.     

Effects of stocking density on growth performance,blood parameters and immunity of growing pigs

This study was conducted to evaluate the effects of different stocking densities on growth performance, blood parameters, intestinal morphology and intestinal immunity of growing pigs. A total of 288 male pigs (44.35 ± 0.50 kg) were randomly assigned to groups with stocking densities of 2.46, 1.23 and 0.82 m²/pig for a month. The results showed that there was no significant difference on growth performance among groups. Pigs in the stocking density of 0.82 m²/pig had the lowest backfat thickness and spleen weight index among groups (P < 0.05). With increasing stocking density, the serum concentrations of blood urea nitrogen (BUN), transglutaminase (TGG), alkaline phosphatase (AKP) and immunoglobulin A (IgA) were increased, and albumin (ALB), albumin-to-globulin ratio (ALB:GLO), insulin-like growth factor-1 (IGF-1) and immunoglobulin (IgM) were decreased (P < 0.05), and cortisol tended to increase and glucose tended to decrease (0.05 < P < 0.1). Compared with the stocking density of 2.46 m²/pig, the ileal villus height and jejunal villus width decreased in stocking densities of 1.23 and 0.82 m²/pig (P < 0.05). The duodenal villus height and ileal villus width in the stocking density of 0.82 m²/pig were the lowest among 3 groups (P < 0.05). The content of immunoglobulin A in duodenum, jejunum and ileum mucosa increased along with increasing density (P < 0.05). The contents of interleukin (IL)-2 in the spleen or liver and IL-10 in the spleen were higher in the stocking density of 0.82 m²/pig than in other 2 groups. These results showed that stocking density could affect the metabolism, intestinal morphology, and immunity of growing pigs and 1.23 m²/pig may be the suitable stocking density for the growing pigs in the present study.     

Effects of grouping unfamiliar cohorts, high ambient temperature and stocking density on live performance of growing pigs

Ninety-six crossbred intact male pigs (34.5 +/- 3.5 kg BW) were allocated by weight and vocalization score to a 2 x 2 x 2 dynamic experimental design including two stocking densities (1 or 2 m(2)/pig), two temperatures (22 degrees C and 30 degrees C), and two short groupings of unfamiliar cohorts (six pigs as one pig per group, and six pigs per group). The study was conducted over 8 wk, and live weight gain (WTG) and feed intake (FI; as-fed basis) were measured weekly. During the first week, pigs were housed in individual pens from four independent rooms. To group pigs, pen partitions were removed. Pigs were grouped in Rooms 2 and 3 from wk 2 to 4, and in Rooms 1 and 4 during wk 7. Temperature was increased from 22 degrees C to 30 degrees C in Rooms 1 and 2 during wk 4 and 7. Pen partitions were replaced in Rooms 2 and 3 at the end of wk 4 and in Rooms 1 and 4 at the end of wk 7 to return pigs to their individual pens. Grouping pigs decreased FI during wk 3 (15.08 +/- 0.43 vs. 14.03 +/- 0.41 kg P < 0.10), and during wk 7 (17.42 +/- 0.46 vs. 14.24 +/- 0.41 kg; P < 0.01). In addition, grouping had a negative effect (P < 0.001) on WTG at wk 3 (7.38 +/- 0.28 vs. 5.71 +/- 0.28 kg) and at wk 7 (6.70 +/- 0.26 vs. 2.99 +/- 0.26 kg). For grouped pigs, raising the temperature decreased (P < 0.01) WTG (7.49 +/- 0.29 vs. 6.41 +/- 0.29 kg during wk 4, and 3.37 +/- 0.38 vs. 2.62 +/- 0.38 kg during wk 7). Mean FI was decreased (P < 0.01) with the 30 degrees C treatment during wk 7 only (15.49 +/- 0.33 kg at 22 degrees C compared with 12.99 +/- 0.33 kg at 30 degrees C). Compensatory feed intake was evident after the treatments had ceased at wk 6, whereby previously heat-treated grouped pigs had a higher FI (17.97 +/- 0.45 kg) than the animals individually housed at 22 degrees C (12.99 +/- 0.33 kg). Stocking density effects were noted after the grouping and high temperature treatments had ceased. For instance, during wk 5, low-density-housed pigs grew faster (P < 0.001) than their high-density counterparts (9.04 +/- 0.38 vs. 7.49 +/- 0.29 kg). In conclusion, under the conditions of this study, the grouping of unfamiliar cohorts and high ambient temperature treatments had a detrimental effect on pig performance, and these effects were reversible.     

Effects of diet and housing density on growth and stomach morphology in pigs.

Two experiments were conducted to evaluate the impact of housing density on the stomach morphology of growing pigs and determine whether there was an interaction between housing density and diet. All diets were corn-soybean meal based. In Exp. 1, 42 barrows (41.0+/-.95 kg BW) were allotted either individually or three pigs per pen to evaluate the effects of crowding on stomach lesions. Pen space per pig was 1.54 and .51 m2, respectively. All pigs were fed a finely ground and pelleted diet (610 microm) for 6 wk. The ADG decreased (P<.05) for the pigs housed three per pen during wk 4 to 6 only. There was no effect of housing density on feed intake or gain/feed ratio. Neither visual nor histological ulcer score differed between the two treatment groups. No stomachs were graded as normal. In Exp. 2, 80 barrows (39.8+/-.9 kg BW) were allotted either two or four pigs per pen. Pen space per pig was .77 and .39 m2, respectively. Half of the pigs in each housing situation were fed a coarse meal diet (1,050 microm), and half of the pigs were fed a finely ground and pelleted diet (577 microm) throughout the 49-d experimental period. Throughout the trial, pigs housed two per pen gained at a greater rate (P<.05) than pigs housed four per pen. From d 14 to the end of the trial, pigs consuming the finely ground and pelleted diet gained at a greater rate (P<.05) than pigs fed the coarse meal diet. The differences in ADG were reflected in final body weight. Stomach weight as a percentage of body weight was higher for animals on the coarse meal diet. Visual and histological ulcer scores were similar, and both were higher (P<.001) on the finely ground and pelleted diet, indicating greater damage. There was no effect of space restriction on stomach morphology. These data show the major effect of diet type on stomach lesions with no interaction with space restriction.     

Effects of dietary tryptophan and stocking density on the performance,meat quality,and metabolic status of broilers

Background

Highly automated cage-rearing systems are becoming increasingly popular in China. However, a high stocking density can cause oxidative stress and decrease broiler performance. The tryptophan (TRP) derivative 5-hydroxytryptophan (5-HT) has been shown to preserve membrane fluidity in birds suffering from oxidative stress. Therefore, this experiment was conducted to determine the effects of dietary TRP supplementation on performance, breast meat quality and oxidative stress in broilers reared in cages with a high or low stocking density.

Methods

Female Arbor Acres broilers (25-d-old, n = 144) were randomly allocated to 1 of 4 treatments. The birds were fed a diet based on corn, soybean meal, cottonseed meal and corn gluten meal containing either 0.18 or 0.27% TRP and were housed with stocking densities of 11 or 15.4 birds/m² in a 2 × 2 factorial experiment. Broiler performance was evaluated from d 25 to 42. Eight birds from each treatment were slaughtered on d 42 and plasma and breast muscle samples were collected to measure biochemical indices.

Results

A higher stocking density tended to be associated with reduced weight gain (P < 0.10), and significantly increased plasma glutamic-pyruvic transaminase (GPT) activity (P < 0.001). Increased dietary TRP significantly reduced the activities of lactic dehydrogenase and GPT while increasing total cholesterol in the plasma (P < 0.01), reducing drip loss of breast muscle (P < 0.10) and improving feed efficiency (P < 0.10).

Conclusions

An increase in dietary TRP, 1.5-fold higher than the standard supplementation level, can alleviate oxidative stress as well as improve welfare and feed efficiency in broilers reared in cages with a high stocking density.     

Effects of temperature stress on growth performance and bacon quality in grow-finish pigs housed at two densities

Managing stressors is essential for optimizing pig growth performance. To determine the effects of temperature and space allocation on growth performance and carcass characteristics, pigs were housed within their thermoneutral zone, at 23.9 degrees C, or above their thermoneutral zone, at 32.2 degrees C, and were provided either 0.66 or 0.93 m(2)/pig for the final 35 d of the grow-finish period. Individual BW were recorded on d 1, 10, 20, and 30. At slaughter, carcass measurements and samples of backfat and belly fat were collected. Final BW was decreased (P < or = 0.05) from 113 to 103 kg for pigs housed at 32.2 degrees C. The ADG was reduced (P < 0.05) for pigs housed at 32.2 degrees C (0.89 vs. 0.54 kg/d), as was G:F (0.28 vs. 0.24). Housing at 0.66 m(2)/pig resulted in pigs that were lighter (P < or = 0.05), at 106 compared with 110 kg, as a result of decreased (P < or = 0.05) ADG (0.78 to 0.65 kg/d) and decreased (P < or = 0.05) G:F (0.275 to 0.255) compared with pigs housed at 0.93 m(2)/pig. Pigs housed at a greater spatial allocation had elevated (P < or = 0.05) ADFI. The interaction of housing at 32.2 degrees C and decreasing spatial allocation increased (P < or = 0.05) the adipose iodine value from 66.8 to 70.4, decreased (P < or = 0.05) the saturated:unsaturated fatty acids ratio from 0.59 to 0.56, and increased (P < or = 0.05) the n-6:n-3 from 23.56 to 25.27. Decreased spatial allocation resulted in decreased (P < or = 0.05) belly weights. Although increased temperature did not affect belly weight, the 32.2 degrees C pigs had decreased (P < or = 0.05) raw and cooked slice weights, increased (P < or = 0.05) percentage lean of bacon, increased (P < or = 0.05) lean:fat ratio of bacon slices, increased (P < or = 0.05) raw slice scores, and increased (P < or = 0.05) quantity of collagen in belly fat. Some of these changes may have resulted from changes in lipid metabolism. Increasing spatial allocation in the 32.2 degrees C pigs decreased fatty acid synthase (P = 0.03) and stearoyl-CoA desaturase- 1 (P = 0.08) mRNA expression in adipose tissue. The results from this study demonstrated decreased growth, carcass lipid quality, and bacon quality in pigs housed at temperatures above the thermoneutral zone; however, increasing the spatial allocation for housing may be a means to ameliorate the negative effects of temperature stress.     

A proteomic reference map for pig serum proteins as a prerequisite for diagnostic applications

A reference protein map for pig serum was set up using two-dimensional electrophoresis (2-DE). Thirty-nine protein chains or spots deriving from 26 different proteins were identified by immunological and mass spectrometric methods. Thus, the positions of most medium to higher abundance serum proteins could be determined on the 2-DE gels. The plasma protein fibrinogen was also included in our study. The overall pig protein pattern differs in some respect to serum/plasma maps of other mammalian species, e.g. in levels and properties of single proteins such as haptoglobin or IgM or in species-specific proteins like pig major acute phase protein. Serum protein maps are a useful tool to get an overview on expressed proteins, and to monitor changes in concentration as well as isotype distribution of the identified proteins. As a consequence, more detailed knowledge on protein pattern changes may give deeper insights into the metabolic development of some pathologic conditions and may lead to putative biomarkers for further investigation. Selected examples for protein pattern changes in pigs infected by a viral (porcine circovirus type 2) and a bacterial (Actinobacillus pleuropneumoniae) pathogen illustrate the usefulness of the method.     

Space requirements of weaned pigs during a sixty-minute transport in summer

Currently, there are no trucking quality assurance recommendations for space allowance of weaned pigs during transport in the United States. The objective of this research was to establish a first estimate of the space requirements of weaned pigs during transport in summer based on measures of animal well-being. A commercial semi-trailer was fitted with compartments that provided 0.05, 0.06, and 0.07 m(2)/pig, which were replicated on the upper and lower deck, with a constant 100 pigs per compartment. Cameras were placed in each experimental compartment to record behaviors and postures of pigs during transport. The frequencies of standing, lying, sitting, standing/rearing on another pig, and lying/huddling on top of another pig were recorded using 1-min scan samples during the entire duration of transport. Blood samples were collected and BW and lesion scores recorded from 32 pigs per space allowance for physiological and immune measures before and after transport (n = 32 pigs/treatment). Pigs were transported for 60 +/- 5 min to the wean-to-finishing site using the same route for each replicate during summer (temperature: 28.4 +/- 1.2 degrees C and relative humidity: 59.8 +/- 4.4% within the trailer). Data were analyzed using the MIXED procedure (SAS Institute Inc., Cary, NC). Cortisol, hematocrit, blood urea nitrogen, total protein, albumin, aspartate aminotransferase, creatine kinase, and gamma-glutamyl transferase increased (P < 0.05) after transport regardless of space allowance. Plasma glucose and BW decreased (P < 0.05) after transport regardless of space allowance. Lesion scores increased (P < 0.001) after transport and were greater (P < 0.05) for barrows compared with gilts. The neutrophil to lymphocyte ratio was greater (P < 0.005) for pigs transported at 0.05 m(2)/pig compared with pigs transported at 0.06 and 0.07 m(2)/pig. Pigs transported at 0.05 m(2)/pig lay down less (P < 0.05) than pigs transported at 0.06 and 0.07 m(2)/pig between 30 and 60 min of transport. Greater neutrophil to lymphocyte ratio and less lying behavior performed by pigs transported at 0.05 m(2)/pig suggest that a minimum space allowance of 0.06 m(2)/pig was preferable when transporting weaned pigs for 60 min during summer in this study.     

Effects of double stocking and weighing frequency on pig performance in wean-to-finish production systems

Two studies were carried out in different wean-to-finish barns to determine the effects of double stocking on pig growth performance. In Study 1, pigs (n = 1,560) were used in a randomized complete block design with a 2 x 2 factorial arrangement of treatments: initial stocking treatment (Single [52 pigs/pen] vs Double [104 pigs/pen] stocked for 10 wk after weaning) and weighing frequency (High [12 times during the study] vs Low [3 times]) on pig performance from weaning (5.9+/-0.01 kg BW; 17 d of age) to harvest (114+/-0.67 kg BW). Floor and feeder space per pig were 0.650 m2 and 4 cm and 0.325 m2 and 2 cm for the single- and double-stocked treatments, respectively. In Study 2, pigs (n = 1,458) were used in a randomized complete block design to evaluate two initial stocking treatments (Single [27 pigs] vs Double [54 pigs] stocked for 10 wk after weaning) on pig performance from weaning (4.8+/-0.01 kg BW; 15 d of age) to harvest (24 wk after weaning). Floor and feeder space per pig were 0.640 m2 and 3.4 cm and 0.320 m2 and 1.7 cm for single- and double-stocked pens, respectively. In both studies, double-stocked pigs were split at the end of wk 10 into two equal-sized groups of similar mean BW and CV of BW, and one group was moved to a different pen in the same building. In Study 1, performance was not affected (P > 0.10) by frequency of weighing. For the first 10 wk after weaning, the Double compared to the Single treatment had lower ADG (7.7 and 7.9%, for Studies 1 and 2, respectively; P < 0.001) and lighter pigs at wk 10 (6.8 and 7.3%, respectively; P < 0.001). During the first 10 wk in Study 1, Double compared to the Single pigs had lower ADFI (7%; P < 0.001) but similar gain:feed (P > 0.10). From wk 11 to harvest, pigs on Double and Single treatments had similar (P > 0.10) ADG in both studies and, in Study 1, ADFI was unaffected by initial stocking treatment, but double-stocked pigs had greater gain:feed (4%, P < 0.01). Double-stocked pigs required an additional 2 d to reach a fixed harvest BW (P < 0.05) in Study 1 and were lighter (4%; P < 0.05) at 24 wk after weaning in Study 2. Carcass measures were similar (P > 0.10) for double- and single-stocked pigs. Double-stocked pigs that were moved at the end of 10 wk had growth performance similar (P > 0.10) to those that remained in the original pen. In summary, double stocking reduced growth rate to 10 wk after weaning but subsequently had no effect on growth rate and improved feed efficiency.     

中草药复合制剂对热应激条件下猪生产性能和血液生化指标的影响

本文研究了藿香、苍术、黄柏和石膏提取物对高温下猪生产性能和血清生化指标的影响。选用2月龄农大I系实验用小型猪48头,分为常温组、高温应激组(高温组)、高温中草药复合制剂组(复合制剂组)3个处理,每组16头猪。于试验的第1、3、6和10天,每组选4头猪,用数字体温表测定肛温,称重,静脉采血后分离血清,测定血清皮质醇、热休克蛋白70含量。结果显示:高温组猪日采食量和日增重显著下降(P<0.05),血清皮质醇、热休克蛋白70含量显著升高(P<0.05)。复合制剂组的日增重和日采食量显著增高(P<0.05),血清皮质醇、热休克蛋白70含量均显著降低(P<0.05)。以上结果提示,复合制剂可以显著改善高温条件下猪的生产性能。     

不同水平脱脂米糠部分替代玉米对苏淮猪氧化还原状态和胆固醇代谢的影响

本试验旨在探讨不同水平脱脂米糠部分替代玉米对苏淮阉公猪氧化还原状态和胆固醇代谢的影响。试验选用21头体重[(62.90±1.12)kg]相近的健康苏淮阉公猪,随机分为对照组(试验Ⅰ组)、试验Ⅱ组和试验Ⅲ组,每组7个重复,每个重复1头猪。试验Ⅰ组猪饲喂基础饲粮,试验Ⅱ组和试验Ⅲ组猪分别以14%和28%的脱脂米糠部分替代基础饲粮中的玉米,并使用豆粕、麸皮和豆油等物质调平基础饲粮与试验饲粮的消化能、粗蛋白质和氨基酸水平。预试期10 d,正试期28 d。结果表明:1)试验Ⅱ组和试验Ⅲ组苏淮猪血清丙二醛(MDA)含量均显著低于试验Ⅰ组(P<0.05);与试验Ⅰ组和试验Ⅲ组相比,试验Ⅱ组苏淮猪血清过氧化氢酶(CAT)活性显著升高(P<0.05);试验Ⅲ组苏淮猪血清铜锌超氧化物歧化酶(CuZn⁃SOD)活性最高,且与试验Ⅰ组相比差异显著(P<0.05);试验Ⅲ组苏淮猪肝脏还原型谷胱甘肽(GSH)含量以及还原型谷胱甘肽/氧化型谷胱甘肽(GSH/GSSG)显著高于试验Ⅰ组(P<0.05)。2)与试验Ⅰ组相比,试验Ⅲ组苏淮猪血清总胆固醇(TC)和低密度脂蛋白胆固醇(LDL⁃C)含量显著升高(P<0.05);各组间肝脏TC和甘油三酯(TG)含量差异均不显著(P>0.05)。3)脱脂米糠部分替代饲粮玉米对苏淮猪肝脏胆固醇-7α-羟化酶1(CYP7α1)和胆固醇-27α-羟化酶1(CYP27α1)mRNA表达量均无显著影响(P>0.05);试验Ⅱ组和试验Ⅲ组苏淮猪肝脏3-羟-3-甲基戊二酸单酰辅酶A还原酶(HMGCR)、固醇调节原件结合蛋白-2(SREBP⁃2)和清道夫受体BI(SR⁃BI)的mRNA表达量显著低于试验Ⅰ组(P<0.05);此外,试验Ⅲ组苏淮猪肝脏低密度脂蛋白受体(LDLR)mRNA表达量最低,且与试验Ⅰ组相比差异显著(P<0.05)。4)将苏淮猪血清TC和LDL⁃C含量分别与血清和肝脏氧化标记物及抗氧化酶做相关性分析表明,同一个体血清TC含量与肝脏GSH含量以及GSH/GSSG呈显著正相关(P<0.05),而血清LDL⁃C含量与肝脏GSH含量以及GSH/GSSG极显著正相关(P<0.01)。综上所述,在本试验条件下,脱脂米糠部分替代饲粮中玉米可部分改变苏淮猪血清和肝脏氧化还原相关酶的活性,并在一定程度上影响机体胆固醇代谢和肝脏胆固醇代谢相关基因的表达。     

Development of an enzyme immuno assay for the determination of porcine haptoglobin in various body fluids: testing the significance of meat juice measurements for quality monitoring programs

Quantification of haptoglobin (Hp), an acute phase protein, in blood is presently discussed as being useful to monitor animal health. We developed an enzyme immuno assay (EIA) which is specific for porcine Hp, is not impaired by hemolytic samples and is sufficiently sensitive to be applied in meat juice. Hp was purified from porcine serum by affinity chromatography on hemoglobin Sepharose followed by gel filtration. A specific rabbit antiserum was obtained. In a competitive approach, biotinylated porcine Hp was used as tracer and incubated with Hp standard or sample in microtiter plates. The limit of detection was 0.02 mg/l, parallelism of sample dilutions was proven; recovery of Hp added to serum samples was 96.4 +/- 4.7%. The coefficients of intra and inter-assay variation were 3.3 (n=5) and 10.2% (n=16), respectively. Hp was reliably quantified in blood serum and plasma, whole blood, saliva and meat juice. For healthy pigs of different ages (4 weeks and 6 months), mean Hp concentrations of about 0.5-0.7 mg/ml were observed. To test the significance of Hp measurements in other matrices, samples were obtained from fattening pigs or from slaughter pigs. Blood serum or plasma was collected in parallel. In whole blood, Hp concentrations were about 40% lower than in plasma, but were closely related (n=24,r=0.85,P<0.001). Saliva Hp concentrations ranged between 0.3 and 3.0 microg/ml and were marginally related with blood plasma concentrations (n=93,r=0.35,P<0.001). From 106 hybrid slaughter pigs (100-110 kg) blood and muscle samples (diaphragmatic pillar, d.p.; m. brachiocephalicus, m.b.) were collected. Meat juice was obtained after freezing and thawing. Concentrations were 0.39+/-0.5 mg/ml in serum and 0.04+/-0.06 mg/ml in meat juice. Hp concentrations in blood were closely correlated with those in d.p. juice (P<0.001,r=0.750) and m.b. juice (P<0.001,r=0.776). In view of the many reports on Hp measurements being predictive for animal health even in the subclinical range, we conclude that Hp quantification in meat juice might be useful to assess meat quality at slaughter and further along the processing chain in terms of animal health.     

Acute feed intake and acute-phase protein responses following a lipopolysaccharide challenge in pigs from two dam lines

This study was conducted to evaluate the response of two dam lines of pigs to acute increases of LPS. Acute-phase proteins were also measured to determine their potential use as biological indicators of the immune response. Thirty-six pigs (initial body weight = 21.3 +/- 0.48 kg) were allotted by dam line (Lines 1 and 2) and sex (castrates and gilts) to one of three LPS dose treatments and penned individually. Treatments were a single i.m. injection of 0 (LPS-0), 25 (LPS-25) or 50 microg LPS/kg body weight (BW) (LPS-50). Acute changes in feed intake were related to a pre-injection baseline intake. Feeders were weighed daily to establish baseline feed intake (average daily feed intake -48 to 0 h prior to injection). The acute feed intake response (AFIR) was computed as the average daily feed intake 0-48 h after injection divided by baseline intake. Serum was harvested at time 0 and 48 h after injection. LPS-0 pigs grew faster and consumed more feed than the LPS-25 or LPS-50 pigs (0.79 kg/d versus 0.51 and 0.50 kg/d; 1.15 kg/d versus 0.96 and 0.89 kg/d, respectively; P<0.001). The AFIR of Line 1 castrates and Line 2 gilts was similar for LPS-25 and LPS-50 treatments, while Line 1 gilts and Line 2 castrates had decreased AFIR with increased LPS dose (sex x line x LPS, P<0.05). Three of 18 castrates died but no gilts died following the LPS challenge (P<0.10). Castrates had higher haptoglobin (Hpt) concentrations than gilts on d 0 (18.1 units of absorption/mg of protein versus 13.1 units of absorption/mg of protein; P<0.03). Line 1 pigs had higher C-reactive protein (CRP) concentrations than Line 2 pigs (P<0.05) on d 0. LPS treatment did not change serum concentrations of CRP, Hpt or ceruloplasmin (Cp). However, the change in serum amyloid A (SAA) concentration decreased quadratically (from 0 to 48 h) with increasing LPS dose (P<0.02). This change in SAA was negatively correlated with the AFIR (r= -0.80; P<0.001). In general, castrates appear to be more sensitive to endotoxin challenges than gilts. Serum amyloid A, but not the other acute-phase proteins evaluated, was a good biological indicator of immune system activation following an acute lipopolysaccharide challenge when compared to the acute change in feed intake.     

Effects of distance moved during loading and floor space on the trailer during transport on losses of market weight pigs on arrival at the packing plant

Effects of distance moved during loading and floor space on the trailer during transport on the incidence of transport losses (dead and nonambulatory pigs) on arrival at the packing plant were evaluated in a study involving 42 loads of pigs (average BW = 131.2 kg, SD 5.05). A split-plot design was used with a 2 x 6 factorial arrangement of the following treatments: 1) distance moved from the pen to the exit of the building [short (0 to 30.5 m) vs. long (61.0 to 91.4 m)] and 2) transport floor space (0.396, 0.415, 0.437, 0.462, 0.489, or 0.520 m(2)/pig). Loading distance treatments (sub-plots) were compared within transport floor space treatments (main plot). Pigs were loaded at the farm using sorting boards and, if necessary, electric goads, transported approximately 3 h to a commercial packing plant and unloaded using livestock paddles. The number of nonambulatory pigs during loading and the number of dead and nonambulatory pigs at the plant were recorded. Nonambulatory pigs were classified as fatigued, injured, or injured and fatigued. In addition, the incidence of pigs exhibiting signs of stress (open-mouth breathing, skin discoloration, and muscle tremors) during loading and unloading was recorded. There were no interactions (P > 0.05) between distance moved and transport floor space treatments. Moving pigs long compared with short distances during loading increased (P < 0.001) the incidence of open-mouth breathing after loading (24.9 vs. 11.0 +/- 1.03%, respectively) and tended to increase the incidence of nonambulatory pigs during loading (0.32 vs. 0.08 +/- 0.09%, respectively; P = 0.09) and of nonambulatory, injured pigs at the plant (0.24 vs. 0.04 +/- 0.07%, respectively; P = 0.06). However, distance moved did not affect other losses at the plant. Total losses at the plant were greater (P < 0.05) for the 3 lowest floor spaces compared with the 2 highest floor spaces, and pigs provided 0.462 m(2)/pig during transport had similar transport losses to those provided 0.489 and 0.520 m(2)/pig (total losses at the plant = 2.84, 1.88, 1.87, 0.98, 0.13, and 0.98 +/- 0.43% of pigs transported, for 0.396, 0.415, 0.437, 0.462, 0.489, and 0.520 m(2)/pig, respectively). These data confirm previous findings that transport floor space has a major effect on transport losses and suggest that these losses are minimized at a floor space of 0.462 m(2)/pig or greater.     

饲养密度与饲粮能量水平对肉仔鸡生长性能及肉品质的影响

本试验旨在研究饲养密度与饲粮能量水平对肉仔鸡生长性能及其肉品质的影响,并探明饲养密度是否影响肉仔鸡的能量需要量。选用 ２周龄体重相近的爱拔益加（ＡＡ）肉仔鸡１１４０只（公母各占 １／２）,采用 ３×４两因子完全随机试验设计,包括 ３个代谢能水平（１２．３３、１２．７５和 １３．１７ＭＪ／ｋｇ）和 ４个饲养密度（１０、１６、２２、２８只／栏）,随机分为 １２个处理,每个处理 ５个重复,设置 ６０个相同的围栏,分栏饲养,围栏有效面积为 １．５ｍ２。正试期 ２８ｄ。结果表明：１）饲养密度和饲粮能量水平影响肉仔鸡的生长性能,但两者之间不存在交互作用（Ｐ＞０．０５）;高密度饲养极显著限制肉仔鸡平均日采食量（Ｐ＜０．０１）,导致平均日增重极显著降低（Ｐ＜０．０１）,但不影响料重比（Ｐ＞０．０５）;高能饲粮极显著降低肉仔鸡料重比（Ｐ＜０．０１）,提高平均日增重和出栏体重（Ｐ＜０．０１）;２）饲养密度对肉仔鸡胴体品质和肉品质影响较小,但饲粮不同能量水平可造成脂肪酸在体内沉积的差异,胸肌中多不饱和脂肪酸、必需脂肪酸含量随饲粮能量水平提高而显著增加（Ｐ＜０．０５）;３）保持良好的饲养环境,饲养密度不会造成肉仔鸡明显的免疫应激差异（Ｐ＞０．０５）。综上所述,饲养密度和饲粮能量水平影响肉仔鸡生长性能,同时能量水平对肉品质造成较大影响。但在良好的饲养环境中,饲养密度并不影响肉仔鸡对能量的需要量,二者之间不存在交互作用。     

Biological responses to porcine respiratory and reproductive syndrome virus in pigs of two genetic populations

One hundred pigs from the NE Index Line (NEI) and 100 Hampshire-Duroc cross pigs (HD) were inoculated intranasally with porcine respiratory and reproductive syndrome virus (PRRSV 97-7895 strain) at 26 d of age to determine whether genetic variation in response to PRRSV exists. An uninfected littermate to each infected pig served as a control. Pigs were from 163 dams and 83 sires. Body weight and rectal temperature were recorded, and blood samples were drawn from each pig on d 0 before inoculation and on d 4, 7, and 14 after inoculation. Pigs were sacrificed on d 14. Lung and bronchial lymph nodes were collected, placed in optimal cutting temperature compound, and frozen at -80 degrees C. The presence of PRRSV in serum and in lung tissue and bronchial lymph nodes was determined by isolation in cell culture. The presence of antibodies in serum collected on d 14 was determined by a commercial ELISA test. Lung tissue was examined microscopically and scored for incidence and severity of lesions (score of 1 to 3; 1 = no or few lesions, and 3 = severe interstitial pneumonia). Data were analyzed with a mixed model that included random sire and dam effects. The interaction of line x treatment was significant (P < 0.001) for weight change and rectal temperature. Un-infected HD pigs gained 0.67 kg more from d 0 to 14 and averaged 0.32 degrees C higher rectal temperature than uninfected NEI pigs (P < 0.001), whereas infected NEI pigs gained 0.34 kg more and had -0.54 degrees C lower temperature than infected HD pigs (P < 0.001). Viremic titer (cell culture infectious dose 50%/mL) was greater (P < 0.05) in HD than NEI at d 4 (10(4.52) vs. 10(4.22)), 7 (10(4.47) vs. 10(3.99)), and 14 (10(3.49) vs. 10(3.23)). Viral titer loads in lung (P = 0.11) and bronchial lymph nodes tended (P = 0.07) to be greater in HD than NEI pigs. Antibody signal-to-positive (S/P) ELISA ratios in infected pigs ranged from 0.18 to 3.38, and 88% had levels > or = 0.40, which is the positive threshold for this ELISA. The S/P range in uninfected pigs was 0 to 1.11, and 99% had levels < or = 0.40. Mean S/P ratio for infected pigs was 0.23 units higher in HD than in NEI (P < 0.001). The HD pigs had a greater incidence of interstitial pneumonia and 0.65 higher mean lesion scores than NEI pigs (P < 0.001). In summary, responses of pigs of the two lines to infection with PRRSV differed, indicating that underlying genetic variation existed.     

饲养密度对秋季多层平养密闭鸭舍环境参数、生产性能与血清生化指标的影响

本研究旨在确定秋季多层平养密闭鸭舍适宜的肉鸭饲养密度。选取3栋条件相同的鸭舍,3个饲养密度设为12、13、14只/m^2,0~14日龄为预试期,试验期为15~40日龄。在38日龄对3个鸭舍纵向不同位置的环境参数、肉鸭体重、血清生化指标进行监测分析,并评估40日龄生产效益。结果发现:随着饲养密度增加鸭舍内湿度和氨气浓度逐渐增加(P<0.01);鸭舍纵向从湿帘端到风机端的温度、CO2和NH3浓度均逐渐升高(P<0.05);随着饲养密度和纵向距湿帘距离增加,肉鸭38日龄体重均呈线性降低(P>0.05);饲养密度增加导致肉鸭血清甘油三酯、葡萄糖、总蛋白和尿酸升高(P<0.05);随着饲养密度增加,肉鸭个体出栏体重和毛利降低,饲养密度为13只/m2时总盈利最高。综上,秋季饲养密度能著影响多层平养密闭鸭舍的环境参数和肉鸭的生长发育,饲养密度为13只/m2时整栋鸭舍的总盈利最优。