E.A. Amoah

A note on the effect of contact with male goats on occurrence of puberty in female goat kids

Twelve British Saanen female kids were exposed to male goats for 1 h daily on 29 July (Ml), 12 on 12 August (M2) and 12 on 27 October (M3), when the kids were, on average, (± s.d.) 136·4 (± 12·2), 150·2 (± 12·8) and 225·4 (± 3·5) days of age, respectively. Blood samples were collected to determine plasma progesterone concentrations from 17 July onwards. By 27 October, 11 and 12 kids from treatments Ml and M2 had attained puberty, compared with no kids from treatment M3. Ten kids from treatment M3 attained puberty after male introduction. The mean ages and dates at puberty for treatments Ml, M2 and M3, respectively, were as follows: 205·5, 215·3 and 233·0 days ( P P P

Reproductive Performance of Female Goats in South )Pacific Countries

Data on reproductive performance were collected from over 255 female goats located on seven islands in five South Pacific countries for three breeding seasons (1984–1986). Data were used to determine the breeding patterns of goats in the various countries. Gestation length for Fiji and Western Samoa averaged 149.5 and 151.3 days, respectively. Litter size ranged between 1 and 3 kids for all does in all five countries. Litter size (LS) was related to doe age (A): LS = 1.8402 + 0.0002A (R2 = 0.07; P < 0.0001) and parity (P): LS = 1.2290 + 0.1214P (R2 = 0.13; P < 0.0001). Birth weight (BW) ranged between 1 and 6 kg and could be described by a multiple regression equation: BW = 2.7564 − 0.3316LS + 0.1863BP (R2 = 0.18; P < 0.0001), where BP is the period of breeding. Kidding interval of goats ranged between a minimum of 166 in Tonga to a maximum of 1100 days in Fiji. Ranges of kidding percentage and sex ratio of kids (F/M+F%) were 138.8–149.0% and 42–61%, respectively.

Superovulation, synchronization and breeding of does

Abstract Goats can be synchronized for breeding at the convenience and advantage of the producer with exogenous hormones like progesterones or analogues of progesterones (e.g. 6α-methyl-17α-acetoxyprogesterone, fluorogestone acetate), in association with pregnant mare serum gonadotropin, human chorionic gonadotropin, porcine follicular stimulating hormone or injections of cycling does with luteolytic agents like cloprostenol which is a prostaglandin analogue. Anestrous does can be primed with progesterone or its analogues resulting in a diestrus condition. At the withdrawal of the priming agents, gonadotropins or gonadotropin releasing hormone (GnRH) can be administered for estrus and ovulation to occur. Exogenous hormones or their combinations including luteinizing hormone, follicular stimulating hormone and estradiols have been used successfully. These hormone combinations may enhance estrus induction soon after cessation of treatment (20–72 h), or duration of estrus (16–48 h), resulting in improved ovulation (1.4–24.5) and conception rate. Return to estrus, especially for anestrous does during the non-breeding season, is rare for does treated with the above methods. However, by administering melatonin to simulate physiological short day-length conditions, does will conveniently cycle several times for breeding. Thus, does can be superovulated and prepared for embryo transfer or in-vitro fertilization anytime during the year.

Performance of yearling goats fed alfalfa and florigraze rhizoma peanut hay

Two trials comparing the nutritional value of peanut (P) hay (Arachis giabrata Benth.) and alfalfa (A) (Medicago sativa L.) hay were conducted. The first involved 45 growing goats (24 Saanen, 11 Alpine, seven Toggenburg and three Nubian) averaging 18.3 kg body weight (BW). Goats had free access to feed and water throughout the 20-week study and were weighed at weekly intervals. They were offered equal amounts of A, P or AP twice daily. Goats fed P consumed approximately the same amount of dry matter (DM) but gained more BW (P<0.10) and were more efficient (P<0.10) in converting DM into gain than those fed A or AP. A balance trial with 16 wether goats (12 Saanen, three Toggenburg and one Alpine) averaging 25.6 kg resulted in higher digestible DM (P<0.05) and digestible cell wall fractions for goats fed P than A. All goats were in positive nitrogen balance, and nitrogen retained as a percentage of intake declined (P<0.08) from 31.0% for goats fed A to 18.4% for those fed AP, with an intermediate value of 26.5% for goats fed P. In these studies, goats utilized the dry matter of P more efficiently for body weight gain.

In vitro fertilization of goat oocytes during the non-breeding season

A total of 12 does, from mixed Swiss breeds (11 Alpine and 1 Saanen), comprising donors (na 6) and recipients (na 6), were used in two experiments during the non-breeding season (January to June 1997) at the Agricultural Research Station of Fort Valley State University, Georgia, USA. Immature cumulus-oocyte complexes (COC) were collected either by laparotomy (surgery, Experiment 2) or aspirated from ovaries obtained from ovariectomized does (Experiment 1). The oocytes were recovered from 2 to 6 mm diameter follicles and matured in vitro for 24 h in TCM-199 medium supplemented with 10% fetal bovine serum (FBS), 100 mg LH/ml, 0.5 mg FSH/ml and 1 mg estradiol 17b/ml at 38.58C in humid 5% CO2 in air. Expanded COC, obtained from 24 h maturation, were fertilized as described by Parrish et al. (Parrish, J.J., Susko-Parrish, J.L., LeibfriedRutledge, M.L., Critser, E.S., Eyestone, W.H., First, N.L., 1986. Theriogenology 25, 591‐600). Methods of oocyte retrieval (laparotomy vs. ovariectomy) did not affect maturation and fertilization rates. Although the cleavage rate was significantly higher for oocytes obtained by ovariectomy (100%) compared to those retrieved after laparotomy (79%; P 0.05) and morula/blastocyst-stage embryos (90% vs. 65%; Pa 0.05) after ovariectomy and laparotomy, respectively. A total of 21 morula/blastocyst-stage embryos were transferred to six recipients. No pregnancy was detected either by progesterone assay or ultrasonography. Results from this study indicate that oocytes from Swiss Alpine and Saanen breeds born and raised under the climate conditions prevailing in Georgia, USA (3285’N latitude and 8388’W longitude) can be successfully matured and fertilized in vitro, during the nonbreeding season, and that embryo production through in vitro fertilization technology may be an alternative approach to circumvent seasonal anestrus in temperate climates. # 2000 Elsevier Science B.V. All rights reserved.

Nutritive value of florigraze rhizoma peanut as an alternative leguminous forage for goats

Two studies were conducted to evaluate growth performance and nitrogen utilization by yearling goats fed alfalfa (A) or florigraze rhizoma peanut meals (Pe). During the 49-day growth trial,36 growing goats (BW 30.1 kg) were randomly assigned to experimental diets containing the same concentration of crude protein (16%), digestible energy (2.67 Mcal·kg−1) Ca (0.84%) and P (0.56%), as-fed. Alfalfa and peanut meal accounted for 10.5% of dry weight in diet A and Pe, respectively, and an equal mixture of the two test forages was included in diet APe. Fifteen castrated male yearling goats (BW 47.9 kg) were used in a balance trial consisting of a 7-day adjustment and a 10-day collection phase. Feed was offered ad libitum and 100% of voluntary intake determined during the preliminary phase, during the growth and balance trials, respectively. Dry matter (DM) intake in the growth trial tended to decline from 1.41 kg for A to 1.36 kg for Pe. Goats fed A or Pe had similar daily gain (191.8 g), which tended to be higher (P<0.11) than APe (179.6 g). During the balance trial, DM and water intakes were unaffected by diet and were 2.23 and 5.97% of BW, respectively. Digestibility of neutral detergent fiber was improved (P<0.07) from 41.1 to 50.9% when goats were fed Pe instead of A. Treatments did not influence amounts of nitrogen consumed, or excreted in feces and urine. Data from both trials demonstrated that A and Pe have comparable nutritional value and both are utilized efficiently by growing goats.

Embryo recovery, evaluation, storage and transfer in goats

Abstract Embryo recovery, manipulation and preservation (frozen at −196°C) with cryoprotective agents like glycerol or dimethyl sulfoxide make future transfer of genetic resources possible. Survival of embryos has been better for those beyond the two-cell stage of development. Positioning transferred embryos in the oviduct or uterus, and ovaries with functional corpora lutea (CL) in the recipient doe are factors affecting successful implantation. Techniques in embryo recovery, temporary storage, longterm preservation of goat embryos, and methods of transfer for successful pregnancy in goats are reviewed. It is concluded that over 70% of fertilized ova can be surgically recovered from most superovulated does using exogenous hormones like equine anterior pituitary extract (HAP) or follicle stimulating hormone (FSH). Embryos, after microscopic morphological evaluation, can be temporarily stored cultured in bicarbonate or phosphate buffer saline medium enriched with homologous goat serum, for 2–3 d at below 10°C, or indefinitely at −196°C in liquid nitrogen. Successful transfer with good embryo survival has to take into consideration the stage of development (2–3 d post fertilization; 2–12-cell stage), rate of ovulation or state of CL of recipients and place of deposition of embryos relative to CL.