Regrouping of pigs by body weight at weaning does not affect growth performance,carcass quality or uniformity at slaughter of heavy weight pigs

We studied the influence of pen uniformity at weaning (7.5 ± 0.6 kg vs. 7.5 ± 1.2 kg body weight (BW ± SD)) and sex on growth performance during the nursery (7.5 to 27.3 kg BW) and the fattening (27.1 to 130.5 kg BW) phases and carcass quality of barrows and castrated females (CF). During the nursery phase, pigs from the more uniform pens had lower feed efficiency (P = 0.05) than pigs from the less uniform pens. Also, barrows had higher average daily feed intake (ADFI) (P < 0.05) and average daily gain (P < 0.001) and better feed efficiency (P < 0.001) than CF. During the fattening phase, initial pen uniformity did not affect growth performance of the pigs but barrows tended (P = 0.08) to have higher ADFI and worse feed efficiency than CF. Trimmed primal cut yield tended to be higher for the more uniform pigs and better for barrows than for CF (P = 0.09). It is concluded that regrouping of the pigs at weaning according to uniformity of BW did not affect growth performance or carcass quality of the pigs at slaughter. Castrated females might be used as an alternative to barrows for the production of carcasses destined to the dry‐cured industry.     

A quantitative ethogram of aggressive and submissive behaviors in recently regrouped pigs

Twenty prepubertal Yorkshire X Hampshire pigs were mixed in groups of four. Their behaviors were recorded on video tape for 48 h, and a detailed behavioral analysis was performed. Aggressive interactions of 10 unique pairs of pigs were observed. Twenty-five distinct behavioral categories were identified in the total data set, which contained 1,846 behaviors. On average, an interacting pair showed 92 behavioral elements (range: 10 to 307). Eighty-one percent of the behaviors observed consisted of bites and pushes given and received. Bites were targeted mainly at the ears (55%), face (17%) and neck (23%). Most bites to the rump and turning the body 180 degrees occurred during the last third of the fight. Pigs that eventually won fights showed higher incidences of ear bites and lower incidences than expected of head-under-head pushing and body-turning. Pigs that lost fights showed higher frequencies of head-under-head pushing and body-turning. Losers also showed a lower frequency of rump biting. Overall, many of the behaviors performed by the losing pigs were followed by the loser receiving an ear bite. Body-turning was a sign of submission and was always preceded by, and often followed, ear-biting. Once a pig showed body-turning, it generally avoided further face-to-face interaction. Behaviors exhibited as signs of submission were found in each of the 10 pairs observed.     

Producing Salmonella-free pigs: a review focusing on interventions at weaning

Salmonella infection in pig production is typically endemic and largely asymptomatic. It is a cause of substantial concern among food safety bodies, prompting voluntary and legislative responses aimed at monitoring and reducing the number of Salmonella-infected animals entering the human food chain. Elimination of the problem at an early stage of production is highly desirable, and to this end the present review examines published evidence on the carriage of Salmonella by piglets before and after weaning, as well as evidence on the dynamics of Salmonella infection in the weaner and grower stages of pig production, the effects of maternal immunity, and risk factors for Salmonella excretion after weaning. Various interventions to reduce or eliminate Salmonella infection in young pigs have been tried, such as vaccination, competitive exclusion, treatments in feed and water, antibiotic administration, disinfection of animals, and segregated weaning to clean accommodation. The evidence on the effectiveness of these is considered, and the last is examined in some detail, as it appears currently to offer the best chance of eliminating Salmonella from growing stock.     

Effect of evening or morning weaning and immediate or delayed feeding on postweaning performance of pigs.

Weanling pigs (n = 176), 21 to 26 d of age (average initial weight, 7.1 kg), were used to evaluate the effects of weaning time (evening vs morning) and feeding time (immediate vs delayed) on postweaning performance. Pigs were randomly allotted within litters to four treatments in a 2 x 2 factorial arrangement as follows: 1) weaning at 2000 with immediate feeding, 2) weaning at 2000 with 12-h delayed feeding, 3) weaning at 0800 with immediate feeding, and 4) weaning at 0800 with 12-h delayed feeding. A 12:12 light:dark photoperiod was maintained. Four pigs were held per pen, and all pigs were given ad libitum access to a 20% CP corn-soybean meal diet with 15% dried whey throughout the 28-d study. The interactions between weaning and feeding times were not significant. During the 28-d period, pigs weaned at 2000 consumed 5% more feed (P less than .10) and grew 6% faster (P less than .05) than pigs weaned at 0800. Feed to gain ratios were similar for both time treatments. Variance of ADG within pens as measured by range, logarithm of variance, and CV were generally smaller for pigs weaned at 2000 than for pigs weaned at 0800 with no effect of feeding time. Pigs fed immediately after weaning and those delayed for 12 h had similar overall feed consumption, ADG, and feed to gain ratios. Weaning pigs in the evening enhanced performance, perhaps by better matching the normal diurnal eating and activity patterns and weaning time.     

Effect of Mycoplasma hyopneumoniae colonization at weaning on disease severity in growing pigs

To determine whether Mycoplasma hyopneumoniae colonization at weaning in off-site weaning systems is associated with the severity of respiratory disease due to this agent in growing pigs, we studied 20 groups, each group representing a different week in production, in sow herds at 3 farms of 3000 sows each that had a prevalence of M. hyopneumoniae colonization at weaning higher than 5%. The calculated sample size for assessment at weaning was 39 piglets for each group under study; 39 litters were randomly selected, and 1 piglet was randomly selected from each litter for testing and ear-tagged. In total, 780 piglets were tested. The presence of M. hyopneumoniae in nasal swabs at weaning was established by nested polymerase chain reaction (PCR). All groups were followed until slaughter, at which time blood samples were collected from each ear-tagged pig to test for M. hyopneumoniae antibodies, bronchial swabs were collected for detection of M. hyopneumoniae DNA by nested PCR, and the lung lesion score and percentage of affected lungs in the same animals were calculated. Correlation analyses showed a positive correlation between colonization at weaning and all 4 dependent variables indicating infection at slaughter: average lung lesion score, percentage of affected lungs, presence of M. hyopneumoniae on the bronchial epithelium, and seroconversion. This study provides evidence that severity of the disease can be predicted by the prevalence at weaning in segregated systems. Therefore, strategies focused on reducing colonization at weaning seem to be important elements in the global control of M. hyopneumoniae in segregated production systems.     

谷氨酰胺在断奶仔猪饲料中的应用效果

选取108头28日龄杜大长三元杂交断奶仔猪,按饲养试验随机分成3组,每组设3个重复,每个重复12头。Ⅰ组为5%乳清粉日粮组、Ⅱ组为0.5%谷氨酰胺二肽日粮组、Ⅲ组为2%乳清粉+0.5%谷氨酰胺二肽日粮组。试验从28日龄开始至52日龄时结束,试验期为24d,进行断奶仔猪日粮中添加谷氨酰胺对提高断奶仔猪生长性能的试验研究。试验结果表明:Ⅱ组(0.5%谷氨酰胺二肽)比对照Ⅰ组(5%乳清粉)平均日增重提高了3.8%,差异不显著(P>0.05);Ⅲ组(0.5%谷氨酰胺二肽+2%乳清粉)比对照Ⅰ组(5%乳清粉)平均日增重提高了19.2%(P<0.05),增重效果显著。这表明断奶仔猪日粮中添加0.5%谷氨酰胺二肽可替代5%的乳清粉,谷氨酰胺和乳清粉联合使用(用0.5%的谷氨酰胺二肽替代3%的乳清粉)对断奶仔猪来说能取得更理想的饲养效果,并且显著降低了饲料成本。在饲料报酬和采食量方面,Ⅱ组(0.5%谷氨酰胺二肽)与对照Ⅰ组(5%乳清粉)相比饲料转化率降低了1.17%,差异不显著(P>0.05);Ⅲ组(0.5%谷氨酰胺二肽+2%乳清粉)与对照Ⅰ组(5%乳清粉)相比饲料转化率提高了9.25%,差异显著(P<0.05)。表明谷氨酰胺能改善仔猪肠道功能,增加营养物质的吸收,谷氨酰胺与乳清粉联合使用可显著提高饲料转化率,同时可促进仔猪的采食量。在仔猪腹泻方面,试验各组的断奶仔猪均保持在一较低水平的腹泻率,并且差异不显著(P>0.05)。     

EM发酵料在培育仔猪中的应用

ＥＭ发酵料在离乳培育仔猪中应用结果表明：仔猪腹泻率试验组为２．２６％,对照组为６７．９０％;死亡率试验组为１．１３％,对照组为７．９１％;育成率试验组为９８．８７％,对照组为９２．０９％,以上两组差异均极显著（Ｐ＜０．０１）。日增重试验组为２５６．００ｇ,对照组１９３．１４ｇ,两组差异显著（Ｐ＜０．０５）。料重比试验组为１．４４,对照组为１．８５。试验组每头仔猪盈利２９２．８２元,对照组每头仔猪盈利２２９．３１元,ＥＭ投入产出比＝１∶１７４,经济效益可观     

Ethologic risks of early weaning in pigs]

Regularities of social behaviour in sheep have been studied in large-scale production conditions. Efforts were made to work out an hypothesis and to determine the extent in which the biosocial relation mother-young one represent a limiting factor for animal sociability during their ontogeny. For this purpose, two forms of weaning were defined and compared: lasting 28 days (early) and 10 days (very early). Sociability of animals in a group and indexes of their sociability (IS) were criterions under study. The IS values in the first form of weaning varied within the values 3.24-4.09. An average IS value was mean = 2.68 and the dynamics of social hierarchy of the group was stable on the 8th day of their age (Fig. 1). The IS values varied within 1.21-4.30 in the second form of weaning. Average IS value of animals in the group was mean = 3.55 and the sociability was stable on the 28th day of their age. The study was aimed at analysing the social adaptation, eventually maladaptation as a potential consequence of deprivation resulting from very early weaning of pigs. Fig. 3 shows the results of research in the form of different indexes of sociability between simulated weanings of pigs, form I--2.68 and form II 3.55. The IS difference is significant at the significance level alpha = 0.01 and alpha = 0.05. This fact confirms hypothesis of social maladaptation as a consequence of social deprivation of young animals very early weaned.(ABSTRACT TRUNCATED AT 250 WORDS)     

Individual risk factors for Mycoplasma hyopneumoniae infections in suckling pigs at the age of weaning

Background

In recent years, the occurrence and the relevance of Mycoplasma hyopneumoniae infections in suckling pigs has been examined in several studies. Whereas most of these studies were focused on sole prevalence estimation within different age groups, follow-up of infected piglets or assessment of pathological findings, none of the studies included a detailed analysis of individual and environmental risk factors. Therefore, the aim of the present study was to investigate the frequency of M. hyopneumoniae infections in suckling pigs of endemically infected herds and to identify individual risk factors potentially influencing the infection status of suckling pigs at the age of weaning.

Results

The animal level prevalence of M. hyopneumoniae infections in suckling pigs examined in three conventional pig breeding herds was 3.6% (41/1127) at the time of weaning. A prevalence of 1.2% was found in the same pigs at the end of their nursery period. In a multivariable Poisson regression model it was found that incidence rate ratios (IRR) for suckling pigs are significantly lower than 1 when teeth grinding was conducted (IRR: 0.10). Moreover, high temperatures in the piglet nest during the first two weeks of life (occasionally >40°C) were associated with a decrease of the probability of an infection (IRR: 0.23-0.40). Contrary, the application of PCV2 vaccines to piglets was associated with an increased infection risk (IRR: 9.72).

Conclusions

Since single infected piglets are supposed to act as initiators for the transmission of this pathogen in nursery and fattening pigs, the elimination of the risk factors described in this study should help to reduce the incidence rate of M. hyopneumoniae infections and thereby might contribute to a reduced probability of high prevalences in older pigs.     

Herd specific risk factors for Mycoplasma hyopneumoniae infections in suckling pigs at the age of weaning

Background

Mycoplasma hyopneumoniae is the etiologic agent of enzootic pneumonia mainly occurring in fattening pigs. It is assumed that horizontal transmission of the pathogen during nursery and growing phase starts with few suckling pigs vertically infected by the sow. The aim of the present study was the exploration of the herd prevalence of M. hyopneumoniae infections in suckling pigs followed by an investigation of various herd specific factors for their potential of influencing the occurrence of this pathogen at the age of weaning.

Results

In this cross-sectional study, 125 breeding herds were examined by taking nasal swabs from 20 suckling pigs in each herd. In total, 3.9% (98/2500) of all nasal swabs were tested positive for M. hyopneumoniae by real-time PCR. Piglets tested positive originated from 46 different herds resulting in an overall herd prevalence of 36.8% (46/125) for M. hyopneumoniae infection in pigs at the age of weaning. While the herds were epidemiologically characterized, the risk for demonstration of M. hyopneumoniae was significantly increased, when the number of purchased gilts per year was more than 120 (OR: 5.8), and when the number of farrowing pens per compartment was higher than 16 (OR: 3.3). In herds with a planned and segregated production, where groups of sows entered previously emptied farrowing units, the risk for demonstration of M. hyopneumoniae in piglets was higher in herds with two or four weeks between batches than in herds with one or three weeks between batches (OR: 2.7).

Conclusions

In this cross-sectional study, several risk factors could be identified enhancing the probability of breeding herds to raise suckling pigs already infected with M. hyopneumoniae at the time of weaning. Interestingly, some factors (farrowing rhythm, gilt acclimatisation issues) were overlapping with those also influencing the seroprevalences among sows or the transmission of the pathogen between older age groups. Taking the multifactorial character of enzootic pneumonia into account, the results of this study substantiate that a comprehensive herd specific prevention programme is a prerequisite to reduce transmission of and disease caused by M. hyopneumoniae.     

Effect of age on absorption and immune responses to weaning or introduction of novel dietary antigens in pigs

Pigs weaned at three weeks old absorb food protein antigens from the intestine. The amount of antigen absorbed declines over the next three weeks, and this decline is associated with an increasing level of serum antibody to the fed proteins. There was no difference in the rate of immune elimination of intravenously injected antigen in fed and unfed controls. The reduction of serum antigen is thus likely to reflect reduced absorption, possibly mediated by locally produced antibody. Pigs weaned at 10 weeks old also absorbed antigens and produced an antibody response when introduced to soya; and after three weeks of feeding soya the absorption of antigen was substantially reduced. This latter exclusion was specific for soya as a second novel protein (ovalbumin) was absorbed when introduced to the diet at this time. At six months, pigs no longer absorbed soya proteins when they were introduced to the diet. Furthermore, pigs of this age had serum 'antibody' to soya and other proteins such as keyhole limpet haemocyanin to which they had never been exposed.     

Effects of neonatal iron status, iron injections at birth, and weaning in young pigs from sows fed either organic or inorganic trace minerals

Second-parity sows (n = 7) were fed diets containing organic or inorganic trace minerals, and their progeny (n = 68) were used to determine the Fe status of pigs at birth and nursing and postweaning phases. The experiment comprised 2 parts, in which the first experiment was a 2 x 2 factorial arrangement. Sow trace mineral (organic vs. inorganic) was the first factor evaluated, and the injection of Fe (0 or 200 mg) to neonatal pigs within litter was the second factor. In Exp. 2, half the pigs in each litter from each neonatal Fe injection group were injected with Fe (0 vs. 200 mg) at weaning as an added factor in a 2 x 2 x 2 factorial arrangement in a split-split-plot design. Weanling pigs were fed diets fortified with 90 mg/kg of Fe (sulfate), but the analyzed indigenous and fortified Fe content was 170 mg/kg. Pigs in both experiments were bled at periodic intervals to determine hemoglobin (Hb) concentration, percentage of hematocrit (Hct), and ceruloplasmin oxidase activity. Neonates and d-2 pigs from sows fed organic trace minerals had lower (P < 0.05) Hb concentrations compared with sows fed inorganic trace minerals, but they had similar percentages of Hct values. Blood Hb seemed to remain lower throughout the nursing period when sows were fed organic vs. inorganic Fe. Pigs without Fe injection had decreased ADG (P < 0.05) from 0 to 7 and 7 to 17 d than pigs injected with Fe. Although Hb values increased when neonatal pigs received Fe injection, they were somewhat lower when sows were fed the organic Fe. Ceruloplasmin oxidase activity was low at birth, increased to weaning in each treatment group, and was greater in pigs without Fe injection at d 13 (P < 0.05) and those from sows fed organic minerals at d 17 (P < 0.01). In Exp. 2, when the Fe-fortified diet was fed, BW and ADG responses were both greater (P < 0.01) to 28 d postweaning when neonates had received Fe injections. Neonates not injected with Fe at birth but injected at weaning had greater ADG, Hb, and Hct values, whereas pigs injected with Fe did not respond to Fe injection at weaning, which resulted in interactions (P < 0.05) in those criteria at most measurement periods. The results indicated a reduced Fe bioavailability when sows were fed the organic Fe source, but this may also have been due to the greater Fe need, lowered Fe status, or both, of the sow because of the greater number of pigs farrowed and heavier litter weights at parturition and weaning. The results also indicated that Fe injections at birth may be critical to achieving maximum pig growth response to weaning. There was no apparent advantage to injecting Fe at weaning when neonatal pigs received Fe injections.     

复合益生菌制剂对断奶仔猪生产性能的影响

试验用复合益生菌制剂由湖南省微生物研究所研制,含活菌数为≥109个／g。复合益生菌制剂1号主要成分为枯草芽孢杆菌、蜡状芽孢杆菌和酵母菌等。复合益生菌制剂2号主要成分为纳豆芽孢杆菌、蜡状芽孢杆菌和酵母菌等。     

断奶仔猪营养性腹泻及其防治措施

1　断奶仔猪的营养生理特点1.1　代谢机能旺盛,相对生长迅速仔猪物质代谢旺盛,生长快,2 0日龄仔猪体重为初生时的4 .5倍,每千克体增重的蛋白质沉积量为9～14 g ,而成年猪每千克体增重沉积的蛋白质仅为0 .3～0 .4 g ,前者是后者的30～35倍。仔猪6 0日龄体重为初生重的15 .7倍,钙