Implications of recent advances in reproductive physiology for reproductive management of goats

Abstract

The control of reproduction in goats is interesting for technical reasons (synchronization of kiddings, adjustment to forage availability or to economy), and for genetic reasons (identification and dissemination of improved genotypes). The use of short-light rhythms leads to markedly increased production of semen per buck and prevents occurrence of a 'resting' season. Recent identification of a bulbourethral lipase in goat spermatozoa opens new perspectives in sperm preservation. Light plus 'short day' treatments also allow induction of out-of-season oestrous cycles and ovulations leading to enhanced fertility. Repeated use of eCG provokes the production of antibodies, delays the timing of ovulation and causes a reduction in fertility after fixed-time artificial insemination. All steps of embryo production, freezing and transfer are now controlled and allow the attainment of satisfactory numbers of kids born per donor female, which are compatible with the development of the technique for exchanging genotypes between countries. In vitro production of embryos allows high development rates to be achieved after in vitro maturation and fertilization of oocytes, and will ensure the production of synchronous populations of one-cell zygotes at the stage required by new biotechnologies.

Incidence of Hydrometra in Goats and Therapeutic Effects

“…Tomislav Barna 1 , Jelena Apić 1 , Dejan Bugarski 1 , Nevena Maksimović 2 , Aleksandar Mašić 3 , Zoran Novaković 4 , Aleksandar Milovanović 1 * 1 Naučni institut za veterinarstvo "Novi Sad", Novi Sad 2 Institut za stočarstvo, Beograd-Zemun 3 Fakultet za ekološku poljoprivredu, Univerzitet Educons, Sremska Kamenica 4 PSS "Novi Sad", Temerinska 131, Novi Sad…”

“…According to Chemineau et al (1999), at least 50% of the cases of hydrometra in goats occur as a consequence of embryo mortality that apparently takes place at a gestational age of about 40 days (Wittek et al, 1998). Also, it could be linked to indiscriminate use of hormones or mating outside the breeding season (Pugh, 2002).…”

Surgical correction of four cases of hydrometra in ewes

“…The cause of hydrometra in sheep remains largely unknown. It has been postulated that there is an association between ovarian follicular cysts and hydrometra but no causative pathophysiological pathway has been clearly identified 15 18–20…”

Open pulled straw vitrification of murine and caprine embryos and timed deep uterine insemination of goats

“…To that end GnRH, serving as ovulation inducing agent in the ovsynch protocol, was replaced by hCG. Short cycles as a sequel to synchronization (Armstrong et al, 1983;Chemineau et al, 1986Chemineau et al, , 1999Cognié et al, 2003) and superovulation treatment (Holtz, 2005) are commonly encountered in goats both with the conventional sponge-eCG protocol and, as indicated in this and a preceding study (Holtz et al, 2008), to an even higher extent with PGF 2α -GnRH synchronized goats. In cows, short cycles were recorded in 16% (Schmitt et al, 1996) and 11% (Geary et al, 2001) of animals subjected to an ovsynch-protocol.…”

“…Cryopreservation of semen from bucks is considered a challenge, as some workers prefer to remove the seminal plasma by centrifugation to protect the spermatozoa from the toxic effect of lysolecithin. Lysolecithin is a by-product of the reaction between an enzyme having a triglyceride lipase activity that originates in the bulbourethral gland (Pellicer-Rubio et al, 1997) and the lecithin of the egg yolk or skim milk contained in the semen diluents used (Chemineau et al, 1999). Centrifugation of semen is detrimental to the plasma membrane of the spermatozoa; possibly more so than the alleged effect of the enzyme.…”