Abstract
An artificial insemination (AI) program using cooled semen was evaluated over a 7-year period in Florida goats. The effect of the following variables on pregnancy rates was analysed: production system, year and season of AI, synchronisation treatment, bucks, AI technicians, semen deposition site, days in milk at AI, milk yield and parity. Animals were reared under field conditions on commercial farms in southern Spain. Semen was collected from nine bucks and cooled at 4ºC until use. A total of 3941 goats were synchronised using intravaginal progesterone sponges and inseminated 46.0 ± 0.5 h. after sponge removal. Pregnancy was diagnosed by ultrasonography 42-46 days after AI, obtaining an average pregnancy rate of 48.7%. Logistic regression showed that production system, AI year and season, bucks and semen deposition site had a significant effect (p<0.05) on pregnancy rate, while the other variables analysed were removed from the model. The final statistical model accounted for 59.7% of the cases analysed, suggesting that other factors not studied here may influence pregnancy rates in Florida goats.
Highlights
The Florida goat is a dairy breed reared in southern Spain, with an average milk yield of 650 kg per goat per year and an average lactation period of 10 months (Sánchez, 2007)
Hormone treatments are required for fixed-time artificial insemination (FTAI) in order to avoid oestrus detection and synchronise oestrus in a group of goats
The present study sought to clarify the effect of different factors (production system, year of AI, season, synchronisation treatment, bucks, AI technicians, semen deposition site, days in milk (DIM) at AI, milk yield and parity) on pregnancy rates after AI with cooled semen in Florida goats reared under commercial farm conditions
Summary
The Florida goat is a dairy breed reared in southern Spain, with an average milk yield of 650 kg per goat per year and an average lactation period of 10 months (Sánchez, 2007). A number of factors are reported to affect the success of AI, including nutrition, breeding season, environmental conditions, parity, breed, farm, depth of semen deposition, extender composition and hormone treatment (Mellado et al, 2004 and 2006; Salvador et al, 2005; Nunes & Salgueiro, 2011).
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