Seasonal variation in semen quality of Dorper rams using different collection techniques

The aim of the study was to evaluate the seasonal variation in semen quality of Dorper rams using different semen collection techniques. The study was carried out from January 2012 to January 2013. A general management programme for health control was followed, with water being provided ad libitum throughout the trial, and all rams being fed a 2.5 kg maintenance diet per day. Eleven mature Dorper rams, recording a mean body weight of 69.6 ± 9.2 kg and mean age of 18 ± 4.7 months, were used in the trial. A group of six rams were trained for semen collection with the aid of the artificial vagina (AV), while in the remaining five rams, semen was collected using the electro ejaculator (EE). Immediately after collection, ejaculates were evaluated macroscopically and microscopically for semen volume, semen colour, semen pH, semen wave motion, sperm motility, sperm cell concentration, sperm viability and morphology. The results of the trial generally showed that semen in Dorper rams may be collected using the AV or EE methods throughout the year. However, an overall significant better semen quality collected by the AV versus the EE collection method was recorded. Generally, semen of significantly higher quality was recorded in summer, autumn and spring (both collection techniques). The tendency in the current trial was that the EE technique of semen collection was the less reliable method. Consequently the AV is recommended as the more acceptable method of semen collection in the Dorper. Winter is not generally recommended for semen collection, especially when using the EE.Keywords: Artificial vagina, electro-ejaculator, season, semen qualit

The effect of dietary lipid sources on layer fertility and hatchability

This study was conducted to investigate the effect of dietary fatty acids (FA) on the fertility and hatchability of laying hens at the end-of-lay period (69 - 77 weeks of age). Five isoenergetic (12.4 MJ ME/kg DM) and isonitrogenous (170 g CP/kg DM) diets were formulated using different lipid sources (30 g/kg inclusion) to manipulate the dietary FA profile. The control diet was formulated using a 50 : 50 blend of linseed and fish oil, while fish oil was used in the polyunsaturated n-3 treatment. Sunflower oil was used in the polyunsaturated n-6 treatment, while in the mono-unsaturated n-9 diet high oleic acid (HO) sunflower oil was used. Lastly, tallow was used as a lipid source in the saturated FA diet. One hundred and twenty five hens (n = 25/treatment) and 50 cockerels (n = 10/treatment) of the Hy-Line Silver-Brown genotype were randomly allocated to the five dietary treatments at 20 weeks of age. From 69 weeks of age, hens were inseminated with 0.06 mL undiluted semen from cockerels within the same dietary treatment. Between 71 and 78 weeks of age (49 days) a total of 588 eggs-per-treatment were collected, individually marked (date and hen number) and incubated in a single-stage still-air incubator. Eggs were candled on D7 and D14 to determine embryonic mortalities and a 24 h window for hatching was allowed (D21 + 24 h). Although the fish oil treatment resulted in the lowest egg weights (59.3 g) and fertility (84.6%), it recorded the highest hatchability (76%). In contrast, the sunflower oil treatment recorded the lowest hatchability (58.2%) of all treatments, despite its high egg fertility (89.6%). Results of the study suggest that the dietary fatty acid content, in particular the n-3 and n-6 levels, need critical consideration in terms of concentration and ratio in the formulation of breeder diets to limit embryonic mortalities during incubation.Keywords: Chicks, embryo, mortality, mono-, polyunsaturated fatty acid