Ram and buck management

Breeding soundness examination (BSE): a decision-making tool that requires a particular guideline for male goats

Breeding soundness examination (BSE) is a common evaluation to predict the reproductive ability of male livestock. The generated guideline for BSE is specified for each animal species to enhance the performance of BSE. However, there is no particular BSE guideline for bucks yet; then, the BSE guidelines for ram and bull are commonly used for bucks. This investigation was conducted to determine the main BSE characteristics and the appropriate age range for assessment in Boer goats. For this purpose, semen was collected using electro-ejaculation, and seminogram variables (semen-BSE traits) were evaluated using conventional methods. The association between common testicular biometric variables (TBVs) and semen-BSE traits were assessed using Pearson's correlation coefficients and multiple linear regression. Logistic regression was used to test the validity of TBVs for the BSE of Boer goats. In this study, a strange appearance of the head of sperm, known as "rod-in-head" (RIH), was observed. The results showed that the appropriate age range for performing BSE in bucks is 12-30 months. Moreover, scrotal length in the range of 10-15.9 cm was the eligible TBV to be used as a predictor for semen-BSE traits. It was suggested that developing a BSE guideline for bucks is necessary for unbiased selection in performing BSE.

Reproductive Management of Rams and Ram Lambs during the Pre-Breeding Season in US Sheep Farms

Simple Summary

Pre-breeding management of rams and their ram lambs is critical for viable, sustainable and profitable farms. A further understanding of the management and selection criteria of the males during pre-breeding enables producers to efficiently use animal resources to maximize the reproductive potential of the animals. The reproductive management of mature rams and their lambs is complex, varying across breeds, farms, and regions of the world. It involves different aspects of animal husbandry, such as genetics, health, nutrition, behavior, economy and physiological and anatomical changes during the non-breeding season. Sound flock management must include an integrative and complete management plan for males and females that provides adequate conditions for the sheep to express their genetic potential and production level. This review article examines some of the key aspects to consider when managing mature rams and ram lambs during the pre-breeding season to ensure proper condition of the males for optimal function during the breeding season.

Abstract

In sheep farms, achieving economic and productive efficiency and sustainability goals is directly related with the reproductive management of the animals. Genetically, the male contribution to the offspring is 50%, but in practical terms, there is a greater potential impact of the ram on reproductive results, because one male has the potential to affect a large group of females and therefore greatly affects the entire flock. Unfortunately, the selection of males for breeding in the US sheep industry has been traditionally conducted based on phenotypical traits, without a genetic/reproductive evaluation, and/or health assessment or records. Therefore, it is important to establish integrative management practices to select the rams and ram lambs to be used in the breeding season. Among these practices are genomic testing, a comprehensive breeding soundness evaluation and assessment of health status and records of the males before the breeding season, to detect and correct potential issues.

Differences in the thermal sensitivity and seminal quality of distinct ovine genotypes raised in tropical conditions

For different ovine breeds to maximize their reproductive capacity in countries with tropical climate, it is important to evaluate their potential for thermal resilience and consequences on their reproductive traits. Therefore, the objective of this study was to evaluate the effect of thermal environment temperatures of climate seasons in a tropical climate region on the surface temperatures of the scrotum, testicular biometric characteristics, seminal quality and serum testosterone concentration of rams of different genotypes. Breeders of four different genotypes (Dorper, n = 8, Texel, n = 8, Santa Inês, n = 9 and Morada Nova, n = 8) were used throughout the four climate seasons. Higher thermal challenge was recorded in the spring and summer. In the summer increase in scrotal surface temperature was detected by infrared thermography (P < 0.05), mainly in the regions of the distal testicular pole and tail of the epididymis. The animals of the Texel genotype had higher rectal temperature in the summer. In spring, this genotype also had the highest testicular pole (32.2 ± 0.5 °C; P < 0.05) and distal (29.9 ± 0.4 °C; P < 0.05) temperatures and a higher mean testicular temperature (31.7 ± 0.4 °C; P < 0.05). The Morada Nova genotype showed a higher surface temperature gradient between testicular poles (2.96 ± 0.1 °C; P < 0.05), especially in spring. Genotype-dependent thermal sensitivity was detected for the thermal gradient between the testicular poles, reflecting the seminal quality. There was a positive correlation of the thermal gradient between testicular poles with sperm membrane integrity and negative correlation with total sperm defects. The Texel genotype showed less progressive motility and higher percentage of sperm defects. There was no difference in testosterone concentration between genotypes and in the different seasons (P > 0.05). Thus, the indigenous genotypes showed a greater capability to maintain the scrotum-testicular thermoregulation. Dorper animals resembled the indigenous sheep genotypes, in terms of seminal characteristics, unlike Texel animals, which showed lower adaptability and lower seminal quality.

Contagious epididymitis due to Brucella ovis: relationship between sexual function, serology and bacterial shedding in semen

BACKGROUND

Contagious Epididymitis (CE) due to Brucella ovis (B. ovis) is a contagious disease that impairs rams' fertility due to epididymis, testicle and accessory sexual gland alterations. An increased incidence of CE has been observed in South Eastern France ("PACA" region) since the Rev.1 vaccination against B. melitensis has been stopped in 2008. The objective of this study was to evaluate the relationship between the infection by B. ovis and the sexual function of rams. Two-hundred eighteen sexually-mature rams, from 11 seropositive flocks, were submitted to a clinical examination of the genital tract, a semen collection by electro-ejaculation for spermogram and culture, and a serological examination for anti-B. ovis antibodies by complement fixation test (CFT) and indirect ELISA (I-ELISA). The relationships between clinical, seminal, bacteriological and serological parameters were studied using the Fisher exact test and a logistic regression model (binomial logit).

RESULTS

B. ovis shedding in semen was significantly associated with seropositivity (CFT and I-ELISA; p < 0.001 and 0.01 respectively), genital tract alterations (p < 0.05) and poor semen quality (p < 0.001). Seropositive rams presented significantly more genital tract alterations (p < 0.001) and a poor seminal score (p < 0.001) than seronegative rams.

CONCLUSIONS

Since semen culture is not routinely feasible in field conditions, a control plan of CE should be based, where Rev.1 vaccination is not possible, on both systematic clinical and serological examination of rams, followed by the culling of seropositive and/or genital tract alterations carrier rams.

Interactions between parasitic infections and reproductive efficiency in sheep

This review article summarises the many reports in the literature, confirming that, in sheep, parasitic infections can adversely affect reproductive efficiency; examples, which refer to all parts of the reproductive cycle of sheep, are as follows: trichostrongylosis in ewe-lambs (which can lead to delayed attainment of puberty), myiosis of the prepuce (which can cause impediment of mating), chorioptic mange or trypanosomosis in rams (which can lead to testicular degeneration or azoospermia, respectively), trypanosomosis or sarcoptic mange in pre-conceptual ewes (which can lead to poor conception rates or reduced number of ovulations, respectively), toxoplasmosis or neosporosis in pregnant ewes (which are causes of abortion), trichostrongylosis or trematode infections in lactating ewes (which can cause reduction of milk yield and can be a risk factor for mastitis, respectively), cryptosporidiosis in newborn lambs (which can be a cause of deaths), coccidiosis in growing pre-weaned lambs (which can cause suboptimal growth rate). In other cases, the reproductive status of the animal can influence the parasitic infection; examples are as follows: the increase in faecal parasitic output during the peri-parturient period (as a consequence of the peri-parturient relaxation of immunity), the heavier trichostrongylid infections of twin lambs compared to lambs from single parities (as a consequence of developmental origin issues in twin lambs). All the above examples support the idea of presence of interactions between parasitic infections and reproductive efficiency in sheep.