Effect of staining and freezing media on sortability of stallion spermatozoa and their post-thaw viability after sex-sorting and cryopreservation

Sex‐sorted, frozen–thawed stallion spermatozoa remain out of reach of commercial horse breeders because of the low efficiency of the sex‐sorting process and unacceptable fertility rates after insemination. Two experiments were designed to test the effects of alternative staining and freezing media to improve the viability of sex‐sorted frozen–thawed stallion spermatozoa. Experiment 1 compared two freezing media, INRA 82^® and a modified lactose‐ethylenediaminetetraacetic acid (EDTA), for the cryopreservation of sex‐sorted stallion spermatozoa. No significant differences between the two freezing media could be identified, suggesting that both cryodiluents would be suitable for incorporation into a sex‐preselection protocol for stallion spermatozoa. Experiment 2 compared Kenney’s modified Tyrode’s (KMT) and Sperm TALP (Sp‐TALP) as the staining and incubation medium for stallion spermatozoa prior to sex‐sorting. A significant increase in the percentage of acrosome‐reacted spermatozoa occurred after staining and incubation in the clarified Sp‐TALP compared with KMT. As no improvements in sorting rates were achieved using Sp‐TALP, it was concluded that stallion sorting protocols could include KMT as the staining and incubation medium while either INRA 82^® or lactose‐EDTA could be employed as a cryodiluents.     

The Use of Sex-Sorted Stallion Semen in Embryo Transfer Programs

Sorting stallion semen into two separate populations of enriched X- or Y-bearing sperm can be done successfully. For this, stallion semen can be shipped to a sorting facility, but the mare must be in close to the sorting laboratory. Fertility rates when using 20-40 million sperm are an acceptable 60% per insemination. The procedure can be implemented in embryo transfer programs, with no deleterious effect on the pregnancy rate or embryonic death.     

Commercial Breeding with Sexed Stallion Semen: Reality or Fiction?

Sorting stallion spermatozoa for the purpose of separating X- and Y-bearing spermatozoal populations has had significant advances in the past 10 years. However, current technology requires that the mare be close to the laboratory processing the semen. The development of procedures to cool and freeze sex-sorted sperm will be critical if this technology is to be embraced by the equine industry worldwide.     

Semiquantitative multi‐analysis of plasma obtained from Romney lambs (Ovis aries) by inductively coupled plasma mass spectrometry,and the classification according to feed type

The establishment of a classification system for domestic animals on consumed feed stuff is thought to be important from both a hygiene and market point of view. We collected plasma samples of Romney lambs (Ovis aries) which were fed one of the following: a herb‐clover mix (n = 10) which included chicory, red clover, white clover and plantain; a plant‐grass mix (n = 10) which included plantain, ryegrass and white clover; or a grass mix (n = 10) which included ryegrass and white clover. A total of 20 elements in plasma samples obtained from the lambs were analyzed using inductively coupled plasma mass spectrometry. The data were then analyzed by principal component analysis. The lambs were divided into three groups on a score plot depending on the different feed conditions. Furthermore, discriminant analyses of the elements were examined, using linear discriminant analysis with forward stepwise regression. This discriminant function correctly classified the samples from each group. The accuracy of classification of each group, as shown by 10‐fold cross‐validation, proved the effectiveness of the established discriminant function. It is concluded that using linear discriminant analysis might be a useful tool for the validation of elements from plasma in lambs grown in different conditions.     

Analysis of the risk of introduction and spread of porcine reproductive and respiratory syndrome virus through importation of raw pigmeat into New Zealand

AIMS: To determine the frequency with which porcine reproductive and respiratory syndrome (PRRS) virus (PRRSv) would become established in a non-commercial pig herd in New Zealand due to illegal feeding of uncooked food waste containing virus-contaminated pigmeat. To determine the likelihood of a single incursion resulting in a multi-farm outbreak of the disease, and describe the spatio-temporal characteristics of such an outbreak.

METHODS: A Monte Carlo simulation model was constructed to determine the expected annual frequency of PRRSv infection being initiated in a non-commercial pig herd as a result of inadvertent feeding of pigmeat imported from countries endemically infected with the disease. Once the likelihood of PRRSv becoming established in a single pig herd was determined, stochastic spatially explicit infectious disease modelling software was utilised to model the temporal and spatial characteristics of the resulting epidemic.

RESULTS: Assuming the proportion of imported pigmeat remained at current levels, consumption patterns of pigmeat in households in New Zealand remained steady, and limited compliance with recently reintroduced regulations to prevent feeding of uncooked food waste, at least 4.3 pig herds per year were predicted to become infected with PRRSv. Simulation modelling of PRRSv epidemics related to initial infection of a non-commercial farm produced an estimate that 36% of these incursions would spread from the initial herd, and that these outbreaks would involve 93 herds on average in the first year. By increasing the estimated persistence of PRRSv infection in small herds, an average of 205 herds became infected in the first year.

CONCLUSIONS: Given a mean of 4.3 infected premises per year and a 36% probability of infection spreading beyond the initial infected herd, there was a 95% likelihood of a multi-farm PRRS outbreak occurring within 3 years.

CLINICAL RELEVANCE: Introduction of PRRSv through importation of virus-contaminated pigmeat presents a high risk for establishment of the disease in the pig industry in New Zealand.     

Effect of Weight Loss in Obese Dogs on Indicators of Renal Function or Disease

Background

Obesity is a common medical disorder in dogs, and can predispose to a number of diseases. Human obesity is a risk factor for the development and progression of chronic kidney disease.

Objectives

To investigate the possible association of weight loss on plasma and renal biomarkers of kidney health.

Animals

Thirty‐seven obese dogs that lost weight were included in the study.

Methods

Prospective observational study. Three novel biomarkers of renal functional impairment, disease, or both (homocysteine, cystatin C, and clusterin), in addition to traditional markers of chronic renal failure (serum urea and creatinine, urine specific gravity [USG], urine protein‐creatinine ratio [UPCR], and urine albumin corrected by creatinine [UAC]) before and after weight loss in dogs with naturally occurring obesity were investigated.

Results

Urea (P = .043) and USG (P = .012) were both greater after weight loss than before loss, whilst UPCR, UAC, and creatinine were less after weight loss (P = .032, P = .006, and P = .026, respectively). Homocysteine (P < .001), cystatin C (P < .001) and clusterin (P < .001) all decreased upon weight loss. Multiple linear regression analysis revealed associations between percentage weight loss (greater weight loss, more lean tissue loss; r = ?0.67, r² = 0.45, P < .001) and before‐loss plasma clusterin concentration (greater clusterin, more lean tissue loss; r = 0.48, r² = 0.23, P = .003).

Conclusion and Clinical Importance

These results suggest possible subclinical alterations in renal function in canine obesity, which improve with weight loss. Further work is required to determine the nature of these alterations and, most notably, the reason for the association between before loss plasma clusterin and subsequent lean tissue loss during weight management.

     

Re: Advances in animal welfare in New Zealand

Extract

The review article which appeared in the Jubilee Issue of the New Zealand Veterinary Journal (Stafford et al 2002) provided a good summary of recent research into the animal suffering associated with normal farming practices and pest control. In many cases, such research has been helpful in making improvements to animal welfare regulations, and the knowledge gained may prove even more useful in making further beneficial changes during the current submission round on codes of ethical conduct.     

The relationship between estimates of ovarian size in live cattle and subsequent measurements post mortem

The reproductive tract of each of 122 cows was palpated transrectally by a veterinarian on the day before they were slaughtered, to obtain estimates of ovarian size and to identify palpable ovarian structures. Reproductive tracts were then retrieved post mortem. Ovarian volumes were recorded and compared with in vivo size scores (coded 1–5; 1 being the smallest). Ovarian volumes averaged 4.0 ml (score l), 7.0 ml (2), 10.0 ml (3), 12.9 ml (4) and 15.9 ml (5). There was a linear increase in ovarian volume of 3.0 ± 0.1 ml per score unit (r² = 0.792). The curvilinear regression included a significant quadratic term (p<0.05), but only accounted proportionally for an additional 0.003 of the sums of squares. Ovarian size score was about proportional to volume and could be used as a non-surgical technique to measure ovarian volume in live cattle.     

Dystocia in beef heifers: A review of genetic and nutritional influences

Breeding beef heifers for the first time at 15 months of age has potential to increase the efficiency of the beef breeding-cow herd. An increased incidence of dystocia in heifers calving at 2 years of age, compared to mature cows, is a major reason many farmers in New Zealand have not adopted the practice. The predominant type of dystocia affecting 2-year-old heifers is feto-maternal disproportion, a condition in which the fetus is too large relative to the size of the heifer's pelvis. Reducing birthweight of the calf is a means of reducing the incidence of dystocia. Birthweight and length of gestation are determined by genotype of the calf, maternal genetic effects and environmental effects.

Bulls with low estimated breeding values for birthweight have been selected for mating heifers; however, the positive genetic correlation between birthweight and mature weight meant that the progeny of these bulls tended to be lighter at finishing, making them less desirable in the beef industry. The genotype of the dam also plays a role in determining the risk of dystocia; the maternal ability of the dam to nurture the fetus influences birth- weight, and the dam's genetic potential for growth influences the size of her pelvic area. Heavy heifers tend to produce high- birthweight calves, counteracting the reduction in the incidence of dystocia resulting from the larger pelvis in larger heifers.

Manipulating feeding level during pregnancy offers an alternative method for manipulating the birthweight of calves. Little is known about the effects of nutrition in early gestation on placental development or birthweight of calves. No differences in the birthweight of calves have been observed in response to variation in feeding in mid-pregnancy, and variable responses in birthweight and the incidence of dystocia to feeding in the third trimester of pregnancy have been reported. Differences in birthweight have not always resulted in differences in the incidence of dystocia, primarily due to differences in liveweight of the heifer also induced by feeding regimens. Variability in the incidence of dystocia in response to feeding level in the third trimester of pregnancy makes it difficult to make recommendations for the feeding of heifers at this stage of gestation. More research is needed into the effects of nutrition in early gestation on fetal and placental development in cattle.