Significant changes in caecal microbial composition and metabolites of weaned piglets after protein restriction and succedent realimentation

The present study aimed to investigate the effects of protein restriction and subsequent realimentation on caecal barrier function, caecal microbial composition and metabolites in weaned piglets. Thirty-six 28-day-old weaned piglets were randomly assigned to a control group and a treatment group. The piglets were fed diets containing 18.83% (normal) or 13.05% (low) of crude protein from the 1st to 14th day, after which all piglets were fed diets containing 18.83% of crude protein from the 15th to 28th day. The results showed that protein restriction increased caecal bacterial diversity and richness as well as the abundance of Ruminococcus 2, Faecalibacterium and Lachnospiraceae_uncultured, but reduced the abundance and the gene copies of Lactobacillus in the treatment group compared with the control group on day 14. Protein restriction also decreased the concentrations of isovaleric acid and total branched-chain fatty acids. During the succedent protein realimentation stage, the abundance of Ruminococcaceae UCG-014 and the concentrations of lactic acid, acetic acid, butyric acid and total short-chain fatty acids were increased in the treatment group on day 28. Furthermore, the ammonia concentration was reduced, while the gene mRNA levels of caecal barrier function were increased in the treatment group both on days 14 and 28. In conclusion, dietary protein restriction and realimentation could change caecal microbial composition and metabolites, and eventually influence caecal barrier function. The present study may provide a new insight into protein restriction and realimentation in weaned piglets.     

Inbreeding depression in Zebu cattle traits

The productivity of herds may be negatively affected by inbreeding depression, and it is important to know how intense is this effect on the livestock performance. We performed a comprehensive analysis involving five Zebu breeds reared in Brazil to estimate inbreeding depression in productive and reproductive traits. Inbreeding depression was estimated for 13 traits by including the individual inbreeding rate as a linear covariate in the standard genetic evaluation models. For all breeds and for almost all traits (no effect was observed on gestation length), the performance of the animals was compromised by an increase in inbreeding. The average inbreeding depression was ?0.222% and ?0.859% per 1% of inbreeding for linear regression coefficients scaled on the percentage of mean (β_m) and standard deviation (β_σ), respectively. The means for β_m (and β_σ) were ?0.269% (?1.202%) for weight/growth traits and ?0.174% (?0.546%) for reproductive traits. Hence, inbreeding depression is more pronounced in weight/growth traits than in reproductive traits. These findings highlight the need for the management of inbreeding in the respective breeding programmes of the breeds studied here.     

Lysine restriction and realimentation affected growth,blood profiles and expression of genes related to protein and fat metabolism in weaned pigs

To investigate the effects of lysine restriction and subsequent realimentation on growth performance, blood profiles and gene expression of leptin and myostatin, 128 weaned pigs [initial body weight (BW) 6.96 ± 1.07 kg, 26 ± 2 days of age] were randomly allotted to four treatments. The starter diets during the first 2 weeks (P1) contained 100%, 80%, 70% or 60% of recommended lysine levels ( National Research Council, 1998 ). Then, common grower 1 and 2 diets were offered for 2 weeks (P2 and P3) each. During P1, average daily gain (ADG) was linearly reduced (p < 0.05) with the increasing levels of lysine restriction. Growth rate was greater in pigs previously fed lysine‐restricted diets than well‐fed pigs although it did not reach a significant level during realimentation. However, the final BW and overall ADG were the lowest (p < 0.05) and F/G was poor in pigs fed 60% lysine diet. Relative visceral organ weights and composition of skeletal muscle were similar (p > 0.05) among the treatment. Blood triglyceride and glucose levels were increased (p < 0.05) during P1, while blood urine nitrogen, total protein and albumin levels were decreased (p < 0.05) during P2 with the reduction in dietary lysine levels. The abundance of myostatin mRNA in skeletal muscle and leptin mRNA in subcutaneous adipose tissue were lower (p < 0.05) in lysine‐restricted pigs than in pigs fed non‐restricted diets. In conclusion, 80% and 70% lysine restriction of starter diets resulted in inferior growth and compensatory growth effect was noted during realimentation, while 60% lysine restriction had a negative influence on growth performance. Moreover, the changes in myostatin and leptin mRNA abundance caused by nutritional manipulations may be involved in the regulation of protein and fat deposition in young pigs.     

Relationships between the degree of food restriction and welfare indices in broiler breeder females

1. Broiler breeder females were fed ad libitum, or according to a commercial food restriction programme or to gain 0.85, 0.70, 0.55, 0.40 or 0.25 of the body weight of ad libitum‐fed birds. Several indices of the welfare of the birds were assessed at 3‐weekly intervals to 18 weeks of age and related to body weight by regression analysis. Results for 6, 12 and 18 weeks of age are presented in detail.

2. Water intake was consistently higher in the 0.25, 0.40 and commercial restriction treatments.

3. There was a negative curvilinear relationship at each age between body weight and the heterophil‐lymphocyte ratio and plasma corticosterone concentration.

4. There was a positive relationship between the plasma concentration of creatine kinase and body weight at 12 and 18 weeks of age. The relationships between body weight and the plasma activity of alkaline phosphatase and aspartate transaminase changed with age and there were no differences between treatments for lactate dehydrogenase.

5. The time spent resting increased with body weight at each age. The relationship between time spent preening and body weight changed with age whereas that for oral activities was similar among restricted birds at 6, and among all treatments at 12 weeks of age. At 18 weeks there was an increase in oral activities with decreasing body weight.

6. Fearfulness was positively related to body weight. The response of the comb to phytohaemagglutinin injection was similar in all treatments and the antibody titre to injections of sheep red blood cells was curvilinear.

7. A principal components analysis of all measured traits at 6, 12 and 18 weeks of age was conducted. Most of the variables were redundant but at least one from each of the different classes of welfare indices was retained at 6 and 12 weeks of age.

8. It was concluded that a body weight during rearing in the range of 0.5 to 0.85 of ad libitum might provide for optimum welfare of broiler breeder females.     

Mother–Offspring Interactions in Zebu Cattle

The knowledge of the interaction between mother and offspring might contribute to enhance the welfare of the offspring and to improve the reproductive efficiency of the cow. However, there is still little information available about such interaction in some cattle breeds. A series of observational studies were set up, addressing the mother–offspring relationships of Nelore, Guzerat and Gyr cattle breeds. Firstly, the behaviour of cows and calves around the time of parturition was described, and then, the underlying factors that affect the calves' survival and development were studied. Special attention was given to the failure or delay in the first suckling. The results together are indicative of genetic variability for some studied variables, indicating the possibility of selection for calf vigour (using latency to stand up and latency to suckle as its indicators) and maternal ability (using percentage of time in contact with the calves), in spite of the estimates of heritability were low and presented high standard deviation for all variables. The individual variability in their suckling behaviour and the efficiency in first suckling cannot be explained by a single isolated underlying factor. By now, there are some results available, although there are many questions without answers. The field is still open for the development of future research.     

Pedigree analysis in the Brazilian Zebu breeds

Zebu breeds play an important role in cattle production systems in Brazil. To assess the genetic variability from animals in the Herd Books of Nelore, Gir and Guzerat breeds, generation intervals, inbreeding, effective population size and parameters of gene origin (effective number of founders, ancestors and founder genomes) were calculated using pedigree records from 1938 to 1998. Breed subdivision was quantified by Wright's F -statistics. Calculations were separately carried out for consecutive 4-year intervals in the period 1979–98. Generation interval was around 8 years for the three breeds. Total inbreeding increased in all the breeds reaching values of 2.13%, 2.28% and 1.75%. Effective population size decreased from 85 to 68 in Nelore, from 70 to 45 in Gir and remained nearly constant around 104 in Guzerat. The quantities assessing the number of contributing ancestors decreased with time in all the breeds, and in the last analysed period the most important ancestor accounted for 14%, 3.1% and 4.1% in Nelore, Gir and Guzerat, respectively. Results indicate that the studied breeds are suffering from a loss of genetic variability which can result in negative effects on breeding and conservation purposes.     

Feed restriction enhances the depressive effects of erythromycin on equine hindgut microbial metabolism in vitro

Equine typholocolitis is a sporadic diarrheal disease causing high mortality rates. One of the risk factors responsible for this is the oral application of the macrolide antibiotic erythromycin. The aim of the present in vitro study was to investigate whether erythromycin in combination with feed restriction provokes changes in microbial hindgut metabolism and could therefore be involved in the pathogenesis of equine typhlocolitis. As application of erythromycin and feed restriction are risk factors for equine typhlocolitis, both factors were chosen to investigate their individual and combined effects on hindgut microbial metabolism. The colon simulation technique (Cositec) was used to evaluate biochemical parameters of microbial metabolism. Production rates of the acetate, proprionate and butyrate were measured as quantitative parameters of microbial fermentation. Application of erythromycin (10 mg/d) predominantly decreased the production rates of propionate. Reducing the fermentable substrate to 30% induced an even more pronounced impairment. The detrimental effects of feed restriction on the production rates of short-chain fatty acids (SCFA) were enhanced when feed restriction was combined with the application of erythromycin. Irrespective of erytrhomycin, the butyrate fermentation rate was completely inhibited by feed restriction within two days after start of restriction. The reduction in butyrate fermentation rate has to be discussed as a pathophysiological factor for the onset of acute typhlocolitis.     

Identification of an introduced bovine herpesvirus type 1 strain in a closed dairy herd by experimental virus reactivation followed by DNA restriction enzyme analysis

In a closed dairy herd in the province of Utrecht in 1995, nine replacement heifers were erroneously intramuscularly vaccinated with Tracherine, a live virus IBR vaccine. More than 18 months later, serology of the herd revealed that a large part of the herd had developed an antibody response towards BHV1 (62 of 87 animals). To investigate whether Tracherine had recirculated on the farm, four BHV1 antibody positive animals, of which two had been vaccinated with Tracherine, were treated with corticosteroids to reactivate latent BHV1. Two virus isolates were obtained and subsequently analysed by resctriction enzyme analysis. Both isolates were identified as BHV1.1 subtypes. One of the isolates was clearly distinct from Tracherine and was most likely a BHV1 field virus. A BHV1 field virus was most likely introduced into the farm even though the herd was closed, the animals had not been in contact with other cattle, and preventive hygienic measures had been implemented. There was no indication that Tracherine had recirculated.     

Postpartum Ovarian Activity in South Asian Zebu Cattle

Timely onset of postpartum ovarian activity is vital for optimal reproductive performance of dairy cows. Much depends upon genetic constitution of an animal although several factors interplay to govern the onset of postpartum ovarian activity. South Asian zebu cattle have much longer service period when compared with other exotic or crossbred cattle reared in the same Asian environment, which suggests differences in their genetic makeup. However, the cows with same genetic configuration expressed better reproductive potential when reared under different environment, such as in Brazil and Mexico, which suggests the role of extrinsic factors such as management, nutrition, environment and disease conditions. Better management of animals (provision of proper shade, water and housing, efficient oestrous detection and timely insemination), good quality nutrition supplemented with appropriate minerals and vitamins, prevention of diseases (vaccination, deworming, suitable therapeutic interventions) and application of biotechnology have helped in improving postpartum ovarian activity and, therefore, reproductive performance of zebu cattle in Asia. No comprehensive study appears to have been carried out on the various aspects of reproduction in zebu cattle reared under South Asian socio-agro-climatic conditions. This paper is a modest effort to collect what ever information available and to critically review the postpartum ovarian activity in zebu cattle with special reference to the effect of the various managemental practices and pharmacological interventions.     

Compensatory growth and sexual maturity in broiler females reared under severe food restriction from day of hatching

1. Compensatory growth and the onset of lay were studied in White Rock broiler females severely restricted in food intake from day of hatching.

2. When changed to feeding ad libitum the restricted birds gained weight rapidly, but stabilised at a mean body weight 500 to 700 g less than that of controls fed ad libitum. Egg production was similar to that of controls.

3. Birds maintained at low mean body weight (2 224 g at 42 weeks) by continued restriction did not come into lay. In groups maintained at somewhat higher mean body weights (2 300 to 2 700 g) for periods of up to a year, some birds came into lay.

4. Birds fed ad libitum showed accelerated development of comb, ovary and oviduct and weighed 2 300 to 2 700 g between 14 and 15 weeks of age, but did not come into lay until 20.5 weeks of age.

5. These results suggest that a minimum body weight and age may be required for the onset of lay in this strain.     

饲料性氟中毒

本文主要论述了饲料性氟中毒的病因和临床症状，防治及影响畜禽对氮耐受性的因素。     

应用斑点酶联免疫吸附试验快速检测饲料中的沙门氏菌

选用硝酸纤维素（NC）膜作固相载体，建立检测沙门氏菌的斑点酶联免疫吸附试验诊断方法，检测成品饲料100份，对沙门氏菌的最低检出量为400个／mL，沙门氏菌阳性检出率43．00％（43／100），常规分离培养阳性检出率为38．00％（38／100），两者符合率为83．72％，差异不显著（P＞0．05）。试验表明该方法简便、特异、快速、结果直观，便于在基层推广使用。     

高效液相色谱法测定饲料中的氯烯雌醚

试验建立了饲料中氯烯雌醚的反相高效液相色谱测定方法。经乙腈提取饲料中的氯烯雌醚,以C18固相萃取小柱进行纯化后,用反相高效液相色谱法检测。氯烯雌醚在0.5～100μg/ml范围内线性关系良好,回归方程Y=138222509X+19447,r=0.9999,饲料中氯烯雌醚的最低检测量为35μg/kg。高、中、低3个浓度的平均加样回收率分别为100.2%、99.10%、99.13%,RSD在0.88%～1.11%范围内。     

血凝法测定饲料中植物凝集素含量

通过研究植物凝集素(lectin)的血细胞凝集活性与其浓度的关系，提出了用血凝法测定饲料中lectin的新方法，并探讨了试样粉碎粒度、脱脂方法、脱脂时间、抽提时间、抽提次数等测定条件对测定结果的影响。结果表明，lectin的活力与浓度之间存在高度线性相关(R^2=0．99)。血凝法测定饲料中lectin的含量时，以样品粉碎过40目、样品与30～60℃石油醚或乙醚比例(W／V)1：8脱脂8h、样品与生理盐水(W／V)1：8抽提8h为宜。在上述条件下测定，回收率可达88％～102％。经过对8种不同的饲料及原料样品lectin含量的测定，平均相对偏差为0．9％～2．4％，变异系数为1．3％～3．3％。结果表明，利用血凝法可快速测定饲料中的lectin含量。     

液相色谱-质谱联用分析饲料中新型的β2-肾上腺素能激动剂——齐帕特罗

建立了饲料中齐帕特罗的液相色谱-质谱联用(LC-MS)检测方法.液相色谱条件为Waters AntantisTM C18色谱柱(150 mm×2.1 mm,3μm);柱温30℃;流动相为乙腈-0.2%甲酸(892,V/V);流速0.2 mL/min;进样量20μL.质谱条件为电喷雾离子源(ESI+),选择离子监测质荷比(m/z)为262、244、202、185带正电荷的准分子离子和碎片离子.齐帕特罗的线性范围为0.01～4μg/mL,最低定量检测限0.01μg/g,回收率为(90±10)%.     

HPLC法测定饲料中喹乙醇的研究

建立了饲料中喹乙醇含量的HPLC测定法，流动相为15％甲醇，流速0．9mL／min，进样量5μL，检测波长260nm。在10～100μg／mL范围内，喹乙醇浓度与峰面积呈良好的线性关系，r为0．99998，回收率85．8％～99．4％，批内变异系数≤5．7％，批间变异系数≤1．1％。24批鸡配合料中未检出喹乙醇，62批鱼饲料中喹乙醇的检出率为8．1％，含量范围为19．7～42．0mg／kg。该方法具有很好的分离度，方法简便、准确、重复性好。     

Early Weaning as Cause of Malnutrition in Half-bred Zebu Calves

Veterinary Research Communications -