Journal
ANIMAL REPRODUCTION SCIENCE
Volume 109, Issue 1-4, Pages 172-188Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.anireprosci.2007.11.026
Keywords
Artificial insemination; Goat; Photoperiodic treatments; Progesterone; Male effect; Synchronisation of oestrus
Funding
- European CRAFT [FA-S2-CT98-9207]
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The response to the male effect was studied in two Saanen and two Alpine flocks over 5 consecutive years. Adult male and female goats were exposed to artificial long days (16 h light and 8h darkness, 16L:8D)in open barns for approximately 3 months (between December 1 and April 15) followed by a natural photoperiod. Goats were treated for 11 days with fluorogestone acetate (FGA) or progesterone (CIDR) immediately before joining. Bucks carrying marking harnesses with adapted aprons joined females 49-63 days after the end of the long-day treatment (between April 30 and June 5) and were left with them for 5 days. In experiment 1 (n = 142), FGA- and CIDR-treated goats were inseminated at a time based on the detection of oestrus. Two insemination groups were distinguished by the occurrence of marking over a 48-h period. Earlier (group 1) and later (group 2) buck-marked goats received one single insemination 12-24 In or 0-12 h after marking, respectively. Unmarked goats were inseminated along with group 2. In experiment 2 (it = 344), FGA-treated goats were inseminated 52 and 70 h (52 h:70 h group) or 52 and 75 h (52 h:75 h group) after joining. In experiment 3 (n = 285), FGA-treated goats were inseminated 52 h (1-AI group) or 52 and 75 h(2-AI g-roup) after joining. In all experiments, an external control group given the classical insemination program was analysed. Over the 5-year period, 92% of the goats exhibited an LH surge during days 1-4 after joining and 98% of them ovulated. Eighty-seven percent of the LH surges detected in milk occurred during the 33-57 h interval after joining, indicating that ovulation took place around 45-69 h. In experiment 1, 96% of the goats were marked 22-70 h after joining. Kidding rate (KR; 78%) was similar between insemination groups and between FGA- and CIDR-treated goats (p > 0.05). Most of the goats (95%) were inseminated during the interval between 15 h before and up to 4 h after ovulation. KR was not affected by the time between detection of marking and insemination or between insemination and ovulation (p > 0.05). In experiment 2, KR (75%) was similar in both insemination groups (P > 0.05). In experiment 3, KR was higher (p < 0.05) in the 1-AI (71%) than the 2-AI group (57%). In all experiments, KR of the control group (68-73%) was similar to that achieved in goats induced to ovulate by the male effect. Prolificity (2.1 +/- 0.7) was not affected by any of the factors examined (p > 0.05). In conclusion, high fertility can be achieved during anoestrus when 1 or 2 inseminations are performed over a 24 h period, determined by oestrus or by the introduction of the buck, if light-treated goats receive 11-day FGA or CIDR treatment and are then induced to ovulate by the male effect. (C) 2007 Elsevier B.V. All rights reserved.
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