Fertility in layer breeders following dietary fatty acid treatments
Olubowale, Olusola Samuel
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A study was conducted to evaluate the effects of dietary lipid sources on the productive and reproductive performances of cockerels and hens between 32 and 78 weeks of age. Five different dietary lipid sources namely fish oil, sunflower oil, high oleic (HO) acid sunflower oil, tallow and an equal (50 : 50) proportion of linseed and fish oil (representing the control diet), were used in formulating the five experimental diets. The objective was to formulate five isoenergetic and isonitrogenous diets, with a constant inclusion level (30 g/kg) of the various supplementary lipid sources, differing only in their fatty acid profile. The experiment on the cockerels (n = 10/treatment) was conducted in two phases- from 35 to 46 weeks (Trial 1) and 69 to 77 weeks of age (Trial 2), running concurrently with the hen (n = 25/treatment) production performance (32 to 78 weeks of age) trial. The following parameters were measured in the cockerels: daily feed intake, body weight, semen volume, sperm concentration, sperm motility, sperm viability and semen ejaculation rate. While lower (P < 0.05) daily feed intake (78.75 g/bird/day), body weight (2499 g), sperm motility (48.1%) and ejaculation rate (79.2%) was recorded in the dietary fish oil (n-3) treatment, a higher (P < 0.05) semen volume (0.42 mL) was recorded in the tallow (SFA) fed cockerels during Trial 1. During Trial 2, no significant differences (P > 0.05) were recorded in most of the parameters measured, except in the body weight of cockerels on the fish oil (n-3) treatment, which was the lowest (P < 0.05). Semen volume of the tallow (SFA) fed cockerels remained high (P < 0.05), with the lowest (P < 0.05) sperm motility (51.6%) however being recorded. The hatchability test conducted during Trial 2 revealed a lower fertility (84.6%), but higher (P < 0.05) hatchability of fertile eggs (76%) in the fish oil (n-3) treatment. The lowest hatchability rates of both eggs set (51.1%) and fertile eggs (58.2%) were recorded in the sunflower (n-6) treatment. All production parameters, except hen-day-egg production were affected (P < 0.05) by the dietary lipid supplementation over a mean period of 46 weeks (33 to 78 weeks of age). The heaviest (P < 0.001) eggs were produced in the sunflower (n-6) treatment group (59.3 g), while the fish oil (n-3) fed hens produced the lightest eggs (57.1 g). This resulted in a higher (P < 0.001) yolk and albumen weights being recorded in the sunflower oil (n-6) treatment. The body weights of the hens (1779 g) fed fish oil (n-3) were also low (P < 0.001), compared to the other treatments. A higher number of sellable eggs, resulting from differences in percentage of cracked eggs, were also recorded in the control (93.3%) and sunflower (93.2%) groups, and compared to those obtained with the tallow (90.8%) treatment. The concentrations of yolk fatty acids and their relative total proportions were influenced by dietary lipid sources, except where oleic fatty acid (n-9) was increased (P < 0.001) in the tallow (SFA) treatment. Consequently, the omega-6 to omega-3 (n-6 : n-3) ratio was lowered according to their dietary sources; 1.52 : 1, 1.14 : 1, 24.39 : 1, 17.21 : 1 and 12.27 : 1 for the control, fish oil (n-3), sunflower (n-6), high oleic sunflower (n-9), and tallow (SFA) treatments, respectively. The present study therefore showed that dietary lipid sources have an effect on the productive and reproductive performance of the cockerels and hens. However, environmental factors such as ambient temperature could influence the utilization of dietary fish oil, as observed in the performance and semen quality of the cockerels.