Variations in the concentrations of the immunoglobulins IgG1, IgG2, IgM and IgA in sheep. 2. Changes in the blood of lambs of different breeds and crossbreeds during the course of the rearing period

The sera of 188 lambs from seven breed groups were analyzed for the concentrations of IgG1, IgG2, IgM and IgA by radial immunodiffusion using monospecific antibodies. From each lamb, 14 blood samples were drawn before and 5 samples after weaning. The following results were obtained: 1. Immunoglobulins could not be detected in sera drawn before the first intake of colostrum. 2. In normally suckling lambs, the peak concentrations of maternal immunoglobulins are attained at 0-18 hrs after birth. They can be assessed in a single blood sample drawn between 18 and 24 hrs. 3. The half-life times of maternal immunoglobulin in lamb sera are 11 days for IgG1, 7 days for IgG2, 6 days for IgM and 18 hours for IgA. 4. The absolute peak heights relate to the amounts of colostrum ingested before 12-18 hrs after birth. 5. The decline of maternal immunoglobulins in lamb sera over-laps with the onset of lamb immunoglobulin synthesis. Renewed rises of concentrations are observed for IgG2 after week 2, for IgM after week 3 and for IgG1 after week 7. The concentrations of IgA remain at the low levels characteristic for the serum of grown sheep. 6. The role of immunoglobulin synthesis in suckling lambs is only briefly and to a small extent reduced after weaning.     

Prevalence of campylobacter in pigs during fattening; an epidemiological study

Summary

Numerous epidemiological reports implicate foods of animal origin as vehicles of human campylobacteriosis. Pigs are probably an important reservoir of campylobacter and a potential source of human infection. In order to improve our knowledge of the epidemiology of campylobacter in pigs, the prevalence of campylobacter and its contamination of feed were monitored in eight pig farms. Faeces samples of pigs aged 11 and 22 weeks, and samples of rectal, ileal and gastric content at a slaughterhouse were collected for bacteriological examination. On 5 farms, subsequent groups of pigs housed in the same stalls was sampled, too. A selection of the campylobacter isolates was characterized with a genetic typing method (RFLP). More than 85% of the sampled porkers were shown to be intestinal carriers of campylobacter at all stages of fattening. Subsequent groups of pigs housed in the same stalls were all carriers, too. The level of campylobacters in the faeces tended to decrease as the pigs got older. There was no difference in the frequency and level of infection with campylobacter between porkers on different farms. The feeding system (wet feed versus dry pellets) did not seem to influence the prevalence of campylobacter although wet feed gave lower counts of Enterobacteriaceae in the faeces.

RFLP‐typing showed a high diversity of campylobacter strains at each sampling on the farm. Similarities were seen between strains isolated during two subsequent samplings of the same group of pigs, but not between strains isolated on the same farm from subsequent groups of pigs housed in the same stall. This suggests that the piglets were already infected at a young age on the breeding farm.     

The Comet assay for detection of DNA damage in canine sperm

Sperm DNA integrity is a fundamental prerequisite in fertilization and embryo development. Among DNA integrity tests, the Comet assay is an accurate and sensitive test for the detection of sperm oxidative damage. The aim of this work was to evaluate sperm oxidative damage using the Comet assay and to study the correlation between Comet and routine assays for the evaluation of semen quality. Dogs were divided in two groups: group A (n = 6), comprising dogs with abnormal spermiogram, that is astheno‐, terato‐ or oligoasthenoteratozoospermic (OAT); and group B (n = 8), comprising normospermic dogs. The distribution of sperm oxidative damage was significantly different between the two groups (p = .001): group A—median: 31.55%, interquartile range (IQR): 30.18–38.01; group B—median: 0.90%, IQR: 0.65–1.96. The correlation between oxidative damage and abnormal morphology was high (r = .846; p < .001). There was a negative correlation between progressive motility and oxidative damage (r = ?.792; p = .001). Basal and oxidative DNA damage of spermatozoa are increased in dogs with non‐normospermic semen. In conclusion, and considering the elevated correlation with classical tests of sperm quality, the Comet assay has ample potential for clinical and research purposes in dogs.     

Reference values of two-dimensional and M-mode echocardiographic measurements as a function of body size in various equine breeds and in ponies

Introduction

The aim of this study was to establish echocardiographic reference values for the equine species using allometric regression equations based on body weight (BW) and thoracic circumference (TC).

New genes for disease resistances through somatic hybridization

Somatic hybridization, a process of combining protoplasts from different plants, can provide new sources of disease resistances for plants. In the case of wild and cultivatedSolanum species, the hybrids express resistances from each partner in the fusion and can often be crossed with cultivars to improve agronomic characteristics of the tubers. Restriction fragment length polymorphism (RFLP) analyses can provide a means for determining that the plants being investigated are actually hybrids as well as a means for following the introgression of DNA into progeny lines. These points are addressed in this paper with specific reference to somatic hybrids betweenSolanum brevidens and potato.     

Factors affecting grazing preference by sheep in a breeding population of tall fescue (Festuca arundinacea Schreb.)

A disadvantage of tall fescue (Festuca arundinacea Schreb.) is its low voluntary intake, resulting in suboptimal performance under grazing. Ideally, selection for this trait is done using grazing animals, but their use in plant breeding programmes is costly and laborious. Repeatable, stable and quantifiable traits linked to animal preference could ease tall fescue breeding. We established a trial to find relationships between the grazing preference of sheep and sward‐ and plant‐related traits. Seventeen genotypes were studied in swards. Sheep grazing preference, pre‐grazing sward height (SH), leaf softness, leaf blade length, width, colour and shear strength, and concentration of fibre, silica, digestible organic matter (DOM) and water‐soluble carbohydrate (WSC) were quantified throughout the growing season. The traits with the strongest correlation with sheep preference were DOM, SH, leaf colour, leaf width and WSC. Leaf softness, silica content and leaf shear strength were not correlated with sheep preference. We conclude that DOM is the trait that offers the best prospects for contributing to progress in tall fescue plant breeding for both intake and feeding value.     

Use of molecular markers to accelerate the breeding of common bean lines resistant to rust and anthracnose

The main goal of this work was to introduce resistance genes for rust, caused by Uromyces appendiculatus, and anthracnose, caused by Colletotrichum lindemuthianum, in an adapted common bean cultivar through marker-assisted backcrossing. DNA fingerprinting was used to select plants genetically closer to the recurrent parent which were also resistant to rust and to race 89 of C. lindemuthianum. DNA samples extracted from the resistant parent (cv. Ouro Negro), the recurrent parent (cv. Rudá), and from BC₁, BC₂ and BC₃ resistant plants were amplified by the RAPD technique. The relative genetic distances in relation to the recurrent parent varied between 9 and 59% for BC₁, 7 and 33% for BC₂, and 0 and 7% for BC₃ resistant plants. After only three backcrosses, five lines resistant to rust and anthracnose with, approximately, 0% genetic distance in relation to the recurrent parent were obtained. These lines underwent field yield tests in two consecutive growing seasons and three of them presented a good yield performance, surpassing in that sense their parents and most of the reference cultivars tested.     

Effect of short-term calf removal at three stages of a follicular wave on fate of a dominant follicle in postpartum beef cows.

The hypothesis that ovulation in response to short-term (48 h) calf removal (CR) is dependent on the developmental stage of the dominant follicle was tested in two studies. The objective of Exp. 1 was to characterize the fate of a dominant follicle following 48-h CR on d 2, 4, or 8 of a postpartum follicular wave. Ovaries of 61 beef cows were examined daily by transrectal ultrasonography starting at d 20 to 21 postpartum. Treatments were no CR (n = 14) and CR on d 2 (n = 12), 4 (n = 16), or 8 (n = 10) of first detected follicular wave. Percentage of cows that ovulated a dominant follicle following treatment was not different among groups (P = 0.62). Maximum size of dominant follicles was larger in cows that ovulated (P = 0.002) than in cows that did not ovulate. The objectives of Exp. 2 were 1) to determine whether a follicular wave could be synchronized in anestrous cows following injection of 1 mg of estradiol benzoate (EB) and 200 mg of progesterone (P4; EB + P4); 2) to characterize the fate of dominant follicles following 48-h CR at three stages of a synchronized follicular wave; and 3) to determine whether estrous cycles of normal length followed ovulation in cows pretreated with EB + P4. Ovaries of 50 anestrous beef cows were examined daily as in Exp. 1. Treatments were sesame oil (SO) injected (i.m.) on d 25 postpartum and no CR (n = 9); EB + P4 and no CR (n = 9); EB + P4 and CR on 6 (n = 12), 8 (n = 9), or 12 (n = 11) d after injection. The EB and P4 injections were given on d 25 postpartum. Variability in day of emergence of subsequent follicular waves was lower in cows receiving EB + P4 than in SO-injected cows (P < 0.05). The percentage of cows that ovulated was not different (P = 0.16), but CR increased the percentage of cows that ovulated when groups that received EB + P4 were compared to the EB + P4 group that did not have CR (53.1 vs 11.1%, respectively; P < 0.05). Maximum diameter of dominant follicles was larger (P = 0.05) in ovulatory follicles. The luteal phase was longer (P < 0.03) in cows receiving EB + P4 injection (10.6 +/- 1.2 d) than in cows receiving SO (4.4 +/- 2.2 d). In summary, the maximum size of ovulatory follicles was greater than that of nonovulatory follicles, the ovulatory response of postpartum anestrous cows was maintained through d 8 of a follicular wave, synchronization of follicular waves was accomplished in postpartum cows using EB + P4, and the subsequent luteal phase length was increased in animals that were administered EB + P4.     

The effect of cell wall degrading enzymes or formic acid on fermentation quality and on digestion of grass silage by cattle

A first cut of timothy, treated with water (untreated), formic acid (FA), cellulase + lactic acid bacteria (CB), cellulase + hemicellulase (CH) or cellulase + hemicellulase + a lignin-modifying enzyme (CHL), was ensiled in pilot-scale silos. Silages, except CB, were fed to four male cattle, each equipped with a rumen and duodenal cannula, in a digestibility trial designed as a 4 × 4 Latin square. The animals were fed a diet of 400 g of concentrate and 600 g of silage at a level of 70 g DM kg^?1 live weight (LW^0·75). All enzyme-treated silages were well-preserved with a more extensive fermentation than in FA silage. The quality of untreated silage was poorer as indicated by higher pH and ammonia-N content. The amount of effluent from enzyme-treated silages ranged from 116 to 127 g kg^?1; for FA and untreated silages values were 101 g kg^?1 and 80 g kg^?1, respectively. Total DM losses from enzyme-treated silages were higher than from FA silage (P < 0·05). No significant differences were noticed between silages in the apparent digestibility of organic matter (OM), neutral-detergent fibre (NDF), acid-detergent fibre (ADF) or nitrogen (N). The apparent digestibility of cellulose was higher with enzyme-treated silages than with FA silage (P < 0·05). The values for microbial N flow at the duodenum were 80·0, 91·9, 80·7 and 70·5g N d^?1, and for the efficiency of rumen microbial N synthesis 38·6, 47·6, 36·9 and 32·5 g N kg^?1 OM apparently digested in the rumen for untreated, FA, CH and CHL silages, respectively. In the rumen the molar proportion of propionate was higher (P < 0·01) and that of butyrate lower (P < 0·01) with enzyme-treated silages when compared with FA silage. The proportion of butyrate was also lower with untreated than with other silages (P < 0·01). The rumen residence time of NDF and ADF was longer (P < 0·05) with enzyme-treated silages than with FA silage.