Relationships between cock semen viability and the fertility of artificially inseminated South African indigenous chicken breeds

Abstract

One hundred and sixty hens and 32 cocks of four different South African indigenous chicken breeds (Naked Neck (NN), Ovambo (OVB), Potchefstroom Koekoek (PK) and Venda (VD) were used in this study. Reproductive performance tests as determined by the number of ejaculations per five minutes of abdominal sexual massage (5ASM) were used to select 16 high performing (HP) and 16 low performing (LP) cocks from a population of 80 cocks. Cocks with

≥2 ejaculates/60 min or ≤1 ejaculate/60 min following ASM were considered as HP or LP cocks, respectively. Semen was collected from each cock following 5ASM, evaluated for semen viability and 0.05 mL diluted semen used to inseminate five hens per breed, in each experimental group. Significant differences in ejaculation rates and semen quality and quantity were recorded in the four breeds of cocks - with the HP cocks of the PK breed producing the highest ejaculation rate (4.1 ± 0.1/60 min), ejaculate volume (0.7 ± 0.02 mL), sperm motility (92 Class Test 2 ± 0.7), percentage live sperm (88.4 ± 0.7%) and total sperm per ejaculate. Significant differences were also recorded in hen fertility and subsequent hatchability of set eggs. Semen from the HP cocks were superior to those from the LP cocks, as evidenced in most of the fertility and hatchability parameters, with PK layers producing eggs that gave the highest average egg weight (58.04 ± 0.9 g), fertility (74.3 ± 0.2%), hatchability of set eggs (84.03 ± 0.7%), percentage of normal chicks (98.1 ± 0.7%) and chick weight (37.9 ± 0.3 g). Results suggest that selection of high performing cocks following five minutes of sexual massage prior to semen collection enhances semen quality and quantity leading to significant improvement in the fertility of artificially inseminated hens.