FERTILITY RESPONSE OF ARTIFICIALLY INSEMINATED BROILER BREEDER HENS TO SEMEN DOSE, INSEMINATION FREQUENCY AND SEMEN DILUTION

Abstract

High ratio of cock to hen required for optimal fertility under natural mating usually leads to increase cost of producing day old chicks. Adoption of Artificial Insemination (AI) could maximise the use of cocks thus reducing production cost. However, required semen dose and frequency of insemination for fertility in breeder chickens have not been documented in Nigeria. Therefore, effects of semen dose, frequency of insemination and semen dilution on egg fertility in broiler breeder chickens were investigated. Marshall broiler breeder hens (n=348, 32 weeks, 2.80±0.34 kg) and 15 cocks (32 weeks, 3.50±0.45 kg) were used. One hundred and twenty hens were randomly divided into five treatments. Treatments one to four were inseminated with 0.02 (containing 5x106 motile spermatozoa, T1), 0.04 (T2), 0.06 (T3) and 0.08 mL (T4) of pooled raw semen harvested from cocks using established technique, while treatment five (T5) hens were mated naturally. Both processes were done for two successive days. Eggs were collected daily and incubated weekly for four weeks to determine fertility and embryo mortality. Four groups of 25 hens each, were inseminated (0.02mL/hen) with undiluted semen at three (D3), six (D6), nine (D9) and twelve days (D12) intervals. Fertility and hatchability were assessed. Another batch of semen were collected and divided into four parts: Undiluted Semen (US), others were diluted at 1:1 with Modified Ringer’s Solution (MRS); Normal Saline (NS) or 1% Dextrose Saline (DS). Spermatozoa motility was measured hourly until it dropped to 50% at 27.96±0.38°C. The treatments were inseminated into 80 hens to determine fertility. In a 3x3 factorial arrangement, another 81 hens were divided into nine groups and inseminated with semen diluted with DS at 1:0 (T1:0), 1:1 (T1:1) and 1:2 (T1:2) each at three, six and nine days intervals to assess fertility and hatchability. Data were analysed using descriptive statistics and ANOVA at α0.05. In the first week, fertility in T1 (94.3±1.9%), T2 (94.5±3.2%), T3 (95.2±1.9%) and T4 (97.1±2.9%) were significantly higher than T5 (76.9±3.0%). Embryo mortality was similar among treatments. Fertility up till 7 days in inseminated hens was above 90%, while at days 8 and 9 it was 87.0±4.7% and 74.2±9.3%, respectively. However, there was a decline from day 10 (69.3±9.3%) to day 22 (0.0±0.0%). Fertility in D3 (80.4±1.8%), D6 (74.3±1.8%) and D9 (76.3±1.5%) were significantly higher than D12 (67.8±2.2%), while hatchability was similar. At third hour, spermatozoa motility was higher in US (71.7±I.7%) and NS (71.5±1.7%) than MRS (61.7±1.7%) and DS (58.3±4.4%), while fertility was highest in DS diluent. Fertility among dilution ratios were similar at 3-day interval but was lower in T1:2 (62.4±7.2%) and T1:1 (50.7±10.8%) than TI:0 (75.8±8.2%) at 6-day interval. At 9-day interval, T1:2 (59.95±1.8%) and TI:1 (66.9±6.1%) were lower than T1:0 (80.70±6.0%), while hatchability was similar. Artificial insemination improved egg fertility. Insemination frequency up to 9 days and semen dilution of 1:2 at 3 days intervals sustained fertility and hatchability in broiler breeder hens. Normal and dextrose saline are suitable as cock semen diluents.