Reproduction in Domestic Animals

Reprod Dom Anim 43 (Suppl. 2), 379–385 (2008); doi: 10.1111/j.1439-0531.2008.01188.xISSN 0936-6768Management of Goat Reproduction and Insemination for Genetic Improvement inFranceB Leboeuf 1 , JA Delgadillo 2 , E Manfredi 3 , A Piace` re 4 , V Cle´ment 4 , P. Martin 5 , M Pellicer 6 , P Boue´5 and R de Cremoux 41 INRA-UEICP, Venours, Rouille´, France; 2 CIRCA, Universidad Autonoma Agraria Antonio Narro, Torreon, Coahuila, Mexico; 3 INRA SAGA;4 Institut de l’Elevage, Castanet-Tolosan cedex; 5 Caprige`ne-France, Agropole, Mignaloux-Beauvoir; 6 Physiologie de la Reproduction et desComportements, UMR 6175 INRA-CNRS-Universite´ de Tours-Haras Nationaux, Nouzilly, FranceContentsReproductive seasonality observed in all breeds of goatsoriginating from temperate latitudes and in some breeds fromsubtropical latitudes can now be controlled by artificialchanges in photoperiod. Short days stimulate sexual activity,while long days inhibit it. This knowledge has allowed thedevelopment of photoperiodic treatments to control sexualactivity in goats, for both the buck and doe. In the Frenchintensive milk production system, goat AI plays an importantrole to control reproduction and, in conjunction with progenytesting, to improve milk production. Most dairy goats areinseminated out of the breeding season with deep frozensemen, after induction of oestrus and ovulation by hormonaltreatments. This protocol provides a kidding rate of approximately65%. New breeding strategies have been developed,based on the buck effect associated with AI, to reduce the useof hormones. With the development of insemination withfrozen semen, a classical selection programme was set up,including planned mating, progeny testing and the diffusion ofproved sires by inseminations in herds. Functional traits havebecome important for efficient breeding schemes in the dairygoat industries. Based on knowledge gained over the pastdecade, the emphasis in selective breeding has been placed onfunctional traits related to udder morphology and health. Newwindows have been opened based on new molecular tools,allowing the detection and mapping of genes of economicimportance.IntroductionGoats and sheep exhibit seasonal changes in reproductiveactivity, accompanied by variations in the availabilityof products over the year. Out-of-breeding-seasonreproduction allows milk and meat production throughoutthe year in accordance with commercial requirementsand consumer expectations. Artificialinsemination has an important role in goat breeding,especially in intensive systems of production, to controlreproduction and, in conjunction with accurate progenytesting, to improve the production of milk, hair andmeat. At the farm level, the control of reproductionallows kidding at a precise season of the year,a synchronization of kidding over a limited period oftime, and facilitates supplementary feeding to meet thedemands of lactation. Most goat milk is processed intohigh-quality cheese. As a result of the evolution ofdemand by consumers for typically regional cheese andfor more quality and safety, dairy goats have to beimproved for production (milk yield) and milk composition(fat and proteins) to remain competitive. Newfunctional traits must also be considered so as to reduceproduction costs and increase product quality and safety.Reproductive Seasonality and Control of theTiming of ReproductionSeasonal variations in female and male sexual activityA reproductive seasonality is observed in most breeds ofgoat originating from high latitudes (>35°) and in somelocal breeds from subtropical latitudes (25°–35°). In theAlpine breed, as in the local does from subtropicalMexico, the breeding season begins in the early autumnand ends in the late winter (Chemineau et al. 1992;Delgadillo et al. 2004a). Males of these breeds alsodisplay wide changes in their sexual activity. In Alpinebucks, the breeding season begins in the early autumnand ends in late winter, while in local bucks fromsubtropical Mexico, it begins in the late spring and endsin the early winter (Delgadillo et al. 1991, 1999). In theseseasonal breeds, sexual behaviour, testicular size, anindex of the spermatogenetic activity, and the quantitativeand qualitative sperm production of bucks decreasesdramatically during the non-breeding season (Delgadilloet al. 1991, 1999).Treatments to control the timing of reproductionPhotoperiodic control of reproductionThe annual reproductive rhythm in breeds of goats andsheep from temperate latitudes and in some local breedsfrom the subtropics is controlled by photoperiod(Delgadillo et al. 2004b; Chemineau et al. 2006). Inartificial conditions, plasma testosterone levels increaseduring short days and decrease during long days(Delgadillo et al. 2004b). In females, ovulations startduring short days and end during long days (Gebbieet al. 1999). In order to manipulate sexual activity, theanimals must perceive alternations between long andshort days to prevent the establishment of sexualrefractoriness.Control of male sexual activity by abolition of seasonalvariations or induction of sexual activity in thenon-breeding seasonIn Alpine and Saanen male goats subjected to alternationsof 1 or 2 months of long days (16 h of light ⁄ day:LD) and 1 or 2 months of short days (8 h of light ⁄ day:SD), marked seasonality of sexual behaviour, testis sizeand quantitative and qualitative sperm production wereabolished or reduced (Delgadillo et al. 1991, 1992).When bucks were collected twice a week during twoconsecutive years, these light-treated males producedÓ 2008 The Authors. Journal compilation Ó 2008 Blackwell Verlag