Reproduction In Goats Research Articles

Strategic nutrient supplementation of free-ranging goats

This paper provides an insight to nutritional limitations of forages and other feed resources and the use of supplementation technology by small farmers to optimize production potential of goats in semiarid range environments. In developing countries, the potential for goat meat production is limited by many environmental and nutritional factors. Free-ranging goats can select their diet from a complex variety of available native plant species. Forage quality and availability are reduced during winter and dry seasons of the year, affecting nutrient intake. Furthermore, the presence of plant secondary metabolites (PSM) in shrub species reduces the availability of energy, increasing the demand for glucose. Supplementation is required to mitigate both, nutrient deficiencies and the effect of PSM toxicity. Supplementation options include leguminous fodders that can serve as good protein and energy sources. However, these fodders need to be irrigated for optimum forage production. Cactus, which requires very little water and is frequently used in some developing countries as feed supplement for ruminants during periods of severe drought, has the disadvantage of high fibre and ash contents, and therefore, low energy and protein densities. Supplementation can also include energy sources such as molasses, cereal grains and byproducts, oilseeds and protein meals, minerals and vitamin A. Feed additives such as ionophores and polyethylene glycol (PEG) still need more evaluation under range conditions. Low-level (0.2–0.4% of body weight) cost-efficient high protein and mineral supplements should be considered carefully. Supplementation should be specific, considering the protein content and mineral profiles of forages in each region. Mineral and protein supplementation of goats consuming high fibre-low protein forages, generally improve intake and performance. Hand-crafted multi-nutrient blocks based on molasses and urea, can stimulate rumen fermentation and supply nutrients needed to complement deficiencies of goats consuming low quality forages. These bocks would require certain degree of compaction and the inclusion of lime (calcium oxide) that reacts with molasses will aid in hardness to restrict intake. They can be transported and managed easily and control supplement intake, while reducing the need of salt as intake regulator and the risk of urea toxicity. Technology transfer to producers should emphasis the use of cost effective and specific nutrient supplementation technology to optimize growth and reproduction of range goats.

Maternal characteristics and environment affect the costs of reproduction in female mountain goats

Maternal characteristics and environment affect the costs of reproduction in female mountain goats

449 EFFECTS OF HORMONAL ADMINISTRATION IN TWO DIFFERENT SHIFTS AND OVULATORY DYNAMICS IN NONBREEDING SEASON ON TOGGENBURG GOATS

Assisted reproduction has been used to optimize reproduction in goats. Ultrasound technology has resulted in a definite gain of knowledge in terms of ovulation time. The aim of this study was to evaluate if the shift (morning or afternoon) of hormonal administration affects different reproductive parameters. This study was conducted from October to December (nonbreeding season) of 2005, in Piau/MG (21°35′S latitude and 43° 15′W longitude), Brazil. Eighteen nulliparous (n = 9) or pluriparous (n = 9) Toggenburg goats were assigned equally according to body weight and condition score into two treatments. Animals received intravaginal sponges (60 mg of MAP, Progespon®, Syntex, Buenos Aires, Argentina) for 6 days plus 37.5 (igof cloprostenol (Prolise®, ARSA S.R.L., Buenos Aires, Argentina) latero-vulvar and 200 IUeCG (Novormon® 5000, Syntex) i.m. 48 h before sponge removal. Procedures were done early in the morning for T1 (10 h) and later in afternoon for T2 (17 h). Goats were monitored twice daily to identify estrous onset and its duration. After sponge removal, ultrasound evaluations were performed every 8 h until ovulation to determine the time, number of ovulations, and ovulatory follicle diameters (5-MHz transducer; Aloka, SSD 500®, Tokyo, Japan). Statistical analyses were performed using all tests at the 95% confidence interval with a SAEG® program (Funarbe, Viçosa, Brazil). The results are presented as mean ± SD. The interval (h) from sponge removal to estrous onset was 30.7 ± 10.6 (T1) and 34.3 ± 17.6 (T2), whereas its duration was 33.3 ± 22.3 (T1) and 34.3 ± 22.4 (T2) (P > 0.05). The interval (h) from sponge removal to ovulation was 54.4 ± 10.2 (T1) and 53.4 ± 12.3 (T2) (P > 0.05). Also, the interval (h) from estrous onset to ovulation was 26.8 ± 8.7 (T1) and 18.1 ± 26.3 (T2). No difference (P > 0.05) was observed in the number of ovulations forT1 (1.89 ± 0.93) or T2 (1.89 ± 0.60). The diameter of the ovulatory follicle (mm) was similar (P > 0.05) for T1 (8.4 ± 1.28) and T2 (7.36 ± 1.15) (P > 0.05). A negative correlation was detected between the interval to estrous onset and diameter of the largest follicle (r = -0.41; P < 0.05), as well as between the interval to estrous onset and the interval from estrus to ovulation (r= -0.73; P < 0.001). A positive correlation was registered between the interval from estrus to ovulation and diameter of the largest follicle (r = 0.65; P < 0.001) and also between the interval from sponge removal to ovulation and diameter of the largest follicle (r = 0.51; P < 0.005) that was evident, indicating that follicles get larger with time. Finally, a negative correlation (r = -0.88; P < 0.05) was obtained between number of ovulations and average diameters of ovulated follicles. These data suggest that Toggenburg goats have a synchronization of ovulation when receiving progestagen short-term protocols in the nonbreeding season, independent of the hormonal dispensing shift. Financial support: Embrapa Goats and Sheep, Tecnopec, Fapemig, CNPq.

Management of Goat Reproduction and Insemination for Genetic Improvement in France

Reproductive seasonality observed in all breeds of goats originating from temperate latitudes and in some breeds from subtropical latitudes can now be controlled by artificial changes in photoperiod. Short days stimulate sexual activity, while long days inhibit it. This knowledge has allowed the development of photoperiodic treatments to control sexual activity in goats, for both the buck and doe. In the French intensive milk production system, goat AI plays an important role to control reproduction and, in conjunction with progeny testing, to improve milk production. Most dairy goats are inseminated out of the breeding season with deep frozen semen, after induction of oestrus and ovulation by hormonal treatments. This protocol provides a kidding rate of approximately 65%. New breeding strategies have been developed, based on the buck effect associated with AI, to reduce the use of hormones. With the development of insemination with frozen semen, a classical selection programme was set up, including planned mating, progeny testing and the diffusion of proved sires by inseminations in herds. Functional traits have become important for efficient breeding schemes in the dairy goat industries. Based on knowledge gained over the past decade, the emphasis in selective breeding has been placed on functional traits related to udder morphology and health. New windows have been opened based on new molecular tools, allowing the detection and mapping of genes of economic importance.

Valuing goat genetic resources: a pro-poor growth strategy in the Kenyan semi-arid tropics

Goats, "the poor man's cow", provide very important genetic resources that can be exploited for continued improvements of the livelihoods of poor livestock keepers in the semi-arid tropics. This study presents the evaluation of the economic values of goat genetic resources (GGRs) in terms of the important non-market traits embedded in goats and how this information can be utilised to improve livelihoods in semi-arid regions. The results obtained from mixed logit models derived from stated choice data collected from 314 respondents in the semi-arid Marsabit district of Kenya reveal that disease resistance is the most highly valued trait whose resultant augmentation results into a welfare improvement of up to KShs.2899. Drought tolerance and milk traits were found to be implicitly valued at KShs.2620 and 1179 respectively. The study further revealed that improvement in milk trait in does, body size and disease resistance traits in bucks, and drought tolerance trait in both does and bucks will collectively improve the producers' welfare hence should be given priority. However, improvement in the reproduction and production ("overall body condition/ meatiness" trait) potential of goats will be worthwhile only if issues concerning access to pasture and water resources are addressed prior and simultaneously.

Use and limitations of alternative feed resources to sustain and improve reproductive performance in sheep and goats

In tropical, semi-arid, and arid areas, animal production is increasingly reliant on supplemental feeding, especially during energetically expensive reproductive seasons. The cost of many traditional feeds restricts their use in many countries, and producers are turning to alternative feed sources. These feed sources may supply the energy and protein requirements for reproduction, but can contain plant secondary compounds that affect various components of the reproductive cycle. In this article, we outline the intake requirements for reproduction in both sexes of sheep and goat, highlighting the importance of timing, as well as quantity, of supplementation on reproductive performance. We investigate examples of various alternative feedstuffs that have been studied throughout the world, such as willow cuttings, lupin seed, feed blocks, and alternative pasture species. We then review what is known about the effects of these feeds on reproduction in sheep and goats, from the well known estrogenic effects to some positive effects from feeds containing condensed tannins.

Thyroid hormones in small ruminants: effects of endogenous, environmental and nutritional factors

Appropriate thyroid gland function and thyroid hormone activity are considered crucial to sustain the productive performance in domestic animals (growth, milk or hair fibre production). Changes of blood thyroid hormone concentrations are an indirect measure of the changes in thyroid gland activity and circulating thyroid hormones can be considered as indicators of the metabolic and nutritional status of the animals. Thyroid hormones play a pivotal role in the mechanisms permitting the animals to live and breed in the surrounding environment. Variations in hormone bioactivity allow the animals to adapt their metabolic balance to different environmental conditions, changes in nutrient requirements and availability, and to homeorhetic changes during different physiological stages. This is particularly important in the free-ranging and grazing animals, such as traditionally reared small ruminants, whose main physiological functions (feed intake, reproduction, hair growth) are markedly seasonal. Many investigations dealt with the involvement of thyroid hormones in the expression of endogenous seasonal rhythms, such as reproduction and hair growth cycles in fibre-producing (wool, mohair, cashmere) sheep and goats. Important knowledge about the pattern of thyroid hormone metabolism and their role in ontogenetic development has been obtained from studies in the ovine foetus and in the newborn. Many endogenous (breed, age, gender, physiological state) and environmental factors (climate, season, with a primary role of nutrition) are able to affect thyroid activity and hormone concentrations in blood, acting at the level of hypothalamus, pituitary and/or thyroid gland, as well as on peripheral monodeiodination. Knowledge on such topics mirror physiological changes and possibly allows the monitoring and manipulation of thyroid physiology, in order to improve animal health, welfare and production.

Effect of photoperiod on milk yield and quality, and reproduction in dairy goats

The objective of this study was to examine the effect of long day photoperiod (LDPP) on milk production and reproduction in milk goats . A total of 79 goats were randomly assigned to three treatment groups blocked by day of kidding. Group 1 (Gr1, n = 26) was subjected to natural photoperiod from January 6 to December 5. Group 2 (Gr2, n = 24) was subjected to LDPP (20 h light, 4 h dark) from June 22 to December 5. Group 3 (Gr3, n = 29) was subjected to LDPP from January 6 to December 6. Weekly milk weights and samples were collected for fat, protein and somatic cell count (SCC) determinations. Blood serum was harvested for progesterone (P4) determination. Results indicated a significant effect ( p < 0.001) between treatments for body weight changes , feed intake and milk yield. Both light treated groups had a significantly higher ( p < 0.001) average daily milk output for the entire lactation period than the control group (G1, 2.193 kg/day; G2, 2.517 kg/day; G3, 2.305 kg/day). Milk fat for the overall lactation was significantly higher in Gr3 (+ 0.19 g/100 ml) than for Gr2 (+ 0.06 g/100 ml) when compared to the control group ( x g/100 ml) under natural photoperiod. Somatic cell counts throughout lactation were significantly ( p < 0.001) lower for Gr2 (1.70 million/ml) and higher for Gr3 (2.03 million/ml), with the control group (Gr1) having an intermediate level (1.96 million/ml). Progesterone levels between June 9 and August 30 indicated that 27%, 48% and 63% of the animals had P4 levels in excess of 1.0 ng/ml serum for Gr1, Gr2 and Gr3, respectively. Pregnancy diagnosis by ultrasound in December revealed that a high number of does in the light treated groups (10 of 37) were pseudo-pregnant when compared with the control group (1 of 21). Although light appeared to be effective in increasing milk production, further investigations are needed to evaluate the effect of LDPP on pseudo-pregnancy in dairy goats.

Milk production, reproductive and growth performances of Damascus goats under northern Cyprus conditions

This experiment was carried out at the Ercan State Farm in northern Cyprus, near Nicosia. This research was focused on the evaluation of milk production, reproduction and growth performances of Damascus goats with the aim of examining methods to improve the milking ability of does nursing kids. The purpose of this research was to evaluate the Damascus goat for milk yield, reproduction and growth performance in the region. According to the data observed, birth rates (based on the number of does bred) for 2001 and 2002 were 70.2 and 80.5%, litter size (based on the number of kids born to the number of does giving birth) for 2001 and 2002 were 1.62 and 1.56, kidding percentage (based on the number of kids born per 100 does brought to the buck) were 114.3 and 125.9%, respectively. Average daily milk yield, lactation milk yield and lactation length of Damascus does were 1.900 ± 0.042, 489.4 ± 12.784 kg and 254.7 ± 2.359 days, respectively. Average 73.4 ± 3.5 kg extra marketable milk was obtained by using our recommended system (30 days suckling + 30 days milking and residual suckling). By this way, milk yield increased 39% in the first 90 days (259.0 kg) and it means 16% on the whole lactation period. Average daily weight gain of kids was determined as 174.1 ± 4.4 g for our recommended system (30 days suckling + 30 days milking and residual suckling).

Recent developments in assisted reproduction in goats

Goats are amongst the most fertile of the domestic species. In the temperate zones seasonality may constitute a limiting factor if intensive production systems are to be employed. When conducting highly organized breeding programmes or utilizing goats as bioreactors in the context of gene pharming, assisted reproduction plays an increasingly important role. This chapter constitutes an update of recent developments in the field of assisted reproduction, including collection and handling of gametes, in vitro fertilization, oestrus control, embryo transfer, conservation and manipulation of gametes and embryos, transgenesis and pregnancy detection. Recently in some of these fields remarkable progress has been made. None the less, imperfections are remaining and sustained efforts will be required to optimize existing and invent new technologies.

Effect of plane of nutrition on seasonality of reproduction in Spanish Payoya goats

The aim of this study was to determine if there is a seasonal pattern of sexual activity in female Payoya goats and if this seasonality could be modulated by nutrition. During the experimental period of 20 months, 43 non-pregnant adults goats were penned under natural photoperiod at latitude 37°15′N. At the onset of the experiment, the animals were allocated to three experimental groups differing in the level of nutrition and whether the animals were entire or ovariectomized does. The high nutrition group (H, n = 16 entire does) receiving 1.5 times maintenance requirements. The low nutrition group (L, n = 16 entire does) and an ovariectomized and oestradiol treated group (OVX, n = 11 ovariectomized does) received a diet supporting their maintenance requirements. The groups were balanced for live weight (LW) and body condition score (BCS) at the beginning of the study. In entire goats, oestrus was tested daily using aproned males, ovulation rate was assessed by laparoscopy 7 days after identification of oestrus and plasma samples were obtained twice per week for progesterone assay. OVX goats were isolated from the other groups and bucks, plasma samples were assayed twice per week for LH and there were four intensive sampling periods during the year to determine LH pulsatility. LW and BCS were recorded for all animals once a week. A clear circannual cycle in live weight change was observed in all experimental groups, being relatively stable or slightly decreasing in summer and autumn and increasing during winter and spring. The effect of exposure to high (H) rather than low (L) nutrition was to cause earlier onset of ovarian activity (5 versus 17 August; P < 0.05), and expression of oestrous (16 August versus 2 September; P < 0.01) and later cessation of reproductive activity (ovulation 11 February versus 17 January; P < 0.01). Consequently, seasonal anoestrus was 32 days shorter in does on the higher plane of nutrition ( P < 0.01). The seasonality of reproductive activity was confirmed in the OVX does, with reduced LH concentrations during spring and summer, and increased LH concentrations in autumn and winter. There was no effect of nutrition on ovulation rate. These results demonstrate that the female Payoya goat exhibits marked reproductive seasonality which is modulated by nutrition but possibly not ovulation rate.

Formalin Affects the Male Reproduction of Black Bengal Goats During Prepubertal Stage Even at Low Concentration: In vivo Study

Formalin Affects the Male Reproduction of Black Bengal Goats During Prepubertal Stage Even at Low Concentration: In vivo Study

Partial cloning and polymorphism of the melatonin1a (Mel1a) receptor gene in two breeds of goat with different reproductive seasonality

The melatonin1a (Mel1a) receptor gene was cloned in two breeds of goat, one with marked seasonal ovarian activity (Alpine breed) and the other with low seasonal variations in ovulatory activity (Creole breed), to determine whether reproductive seasonality is related to the structure of the Mel1a gene. The main part of exon II was amplified by PCR using sheep sense and antisense primers in 17 Alpine and 13 Creole goats, and cDNAs were subcloned and sequenced in both directions. The results indicate the presence of an identical sequence in 12 of the 30 animals, that is, six Alpine and six Creole goats. The greatest similarity in the 784 nucleotides of exon II (primers excluded) that was obtained was found with ovine Mel1a receptor sequence (98.4%) and the differences consisted of 12 nucleotide and four amino acid changes. The presence of seven mutations compared with the previous reference sequence was observed and their combinations indicated the presence of at least five other alleles; one mutation resulted in a change in one amino acid in three Alpine goats. No difference in allelic distribution was observed between the two breeds. The results indicate that no relationship could be established between the Mel1a receptor gene structure and the expression of seasonality of reproduction in goats.

Effects of N-methyl-D,L-aspartate on LH, GH, and testosterone secretion in goat bucks maintained under long or short photoperiods.

Photoperiod modulates reproduction in goats. We tested the hypothesis that the excitatory glutamatergic tone is reduced in the photoinhibited goat. The objectives of this study were to determine the effect of photoperiod and glutamatergic stimulation on LH, GH, and testosterone (T) secretion in goat bucks. Eight mature, intact bucks were used in two simultaneous 4 x 4 Latin square designs. Variables were two photoperiod regimens (short day; SD, 10 h light:14 h dark, n = 4; vs long day; LD, 16 h light:8 h dark, n = 4) and four doses of N-methyl-D-L-aspartate (NMA; 0, 1, 2 and 4 mg/kg BW, i.v.). Venous blood was obtained for 2 h before and after NMA injection, followed by GnRH injection and then a final 1 h of sampling. Injection of NMA increased (P < 0.002) LH secretion within 20 min. This increase was sustained for 120 min, but the response was most pronounced in LD goats. The increase in mean LH was associated with a concomitant dose-dependent increase in pulse frequency (P < 0.006). However, NMA treatment had no effect (P > 0.10) on LH pulse amplitude. The release of LH after injection of GnRH was not affected by photoperiod. Exposure of bucks to LD reduced T secretion relative to that of SD bucks (P < 0.01). However, GH secretion was enhanced in LD bucks (P< 0.001). The response of GH to NMA was dependent on photoperiod history. A highly significant immediate and sustained increase (P < 0.001) was observed in LD but not in SD bucks within 10 min. Overall, a dose-dependent increase (P < 0.01) in T secretion was stimulated by NMA in both LD and SD bucks. These results indicate that NMA receptors may be involved in the regulation of LH, GH, and testosterone secretion in the goat. Furthermore, length of day influences GH secretion in the goat and NMA receptor activation had divergent effects on the secretion of this hormone.

Growth and sexual development of Etawah-cross kids from does of different levels of milk production

The experiment was conducted to evaluate growth and sexual development of female Etawah-cross kids of the progeny of the does with low (Group L), medium (Group M) and high (Group H) milk production. The does were fed King grass ( Pennisetum purpureophoides) (about 2% DM of liveweight) and 400 g/head of concentrate. The amount of concentrate was increased to 600 g/head during the last two months of pregnancy period and during lactation. Kids were weaned at four months of age. Thereafter, they were reared in group and were fed King grass and concentrate. The animals were weighed every two weeks. A mature vasectomized buck were joined in each group to detect the onset of first oestrus (puberty). When kids reached puberty and had a liveweight of about 20 kg, they were mated with intact buck. Ovulation rate, progesterone profiles and fertility were observed. The results showed that pre-weaning growth rates of kids in all three groups were not significantly different (67.0 vs 74.9 vs 70.5 g/day, P>0.05). At six and 12 months of ages, Groups L and M had almost the same liveweight which were higher than Group H. Consequently, Groups L and M reached puberty about 3 - 6 weeks earlier than Group H. The average liveweight at puberty was 19.9, 18.2 and 18.8 kg for Groups L, M and H, respectively, or at about 57.1-69.8% (average 63.2%) of mature liveweight. The pregnancy rate following first mating was relatively high (67-73%) and all does were pregnant in the following mating. Average ovulation rate at conception were low (1.1) in all groups. It was concluded that differences in milk production of the does did not significantly affect post-weaning growth and sexual development and performances of kids. Other factors at certain age or growth phases might be more important to affect growth and reproduction of Etawah-cross goat, and this may warrant further study. Key words : Growth, reproduction, Etawah-cross does

Life-History Effects of Chemical Immobilization and Radiocollars on Mountain Goats

To assess the potential effect of our research activities on mountain goats (Oreamnos americanus), we tested for long-term behavioral, reproductive, and survival effects of immobilizing and radiocollanng goats in an unhunted population in Alberta, Canada. Chemical immobilization of females with xylazine hydrochloride 1-5 months before rut decreased kid production the following year for 3 and 4 year olds (P = 0.02), but not for older females (P = 0.67). Following capture, drugged females abandoned their kids more often than undrugged females (16 vs. 2%; P = 0.02), and abandonment decreased kid survival (P 0.10). Chemical immobilization did not affect survival, foraging efficiency, or time spent alert for either sex (P > 0.20). Radiocollars had no effect on kid production or female dominance status and did not affect survival, foraging efficiency, or time spent alert for either sex (P > 0.10). Overwinter survival of captured and uncaptured kids did not differ. Kids with radiocollars appeared to have lower survival than uncollared kids, but the effect was not significant (P = 0.16). Our results suggest that handling affected reproduction and survival of mountain goats and underline the need to test for similar effects in wildlife field studies. We provide guidelines to reduce unwanted life-history effects on captured mountain goats.

Growth and Reproductive Performance of Small Ruminants under Intergrated Livestock-Oil Palm Production System

The effects of supplementation with mixed fodder or concentrate were investigated on the performance of a) growth of male lambs;md kids grazing extensively under oil palm trees and b) reproduction of ewes and goats stall-fed with native herbage. Supplemented kids and lambs had higher average daily weight gain than controls but the effect was only significant for those which received concentrate (p 0.05) on the reproductive performance of ewes apart fi om highest body weight of first lambing in animals supplemented with concentrate (p < 0.05). Native herbage available under oil palm trees of 5 years old was sufficient for growth and reproduction of sheep and goats. Concentrate was better than mixed fodder as supplement for enhancing the reproductive performance of goats but both appeared to have limited effects on the performance of reproduction in ewes and growth in male kids.

Book Reviews

Book reviewed in this article: A Biographical History of Veterinary Pathology , LZ Saunders, Allen Press Inc Kansas The Immunology of Host‐Ectoparasitic Arthropod Relationships , edited by SK Wikel Pastures for Horses: A Winning Resource A Avery, Rural Industries Research and Development Corp Bovine Ephemeral Fever and Related Rhabdoviruses , editors TD St George, MF Uren, PL Young and D Hoffmann Managing a Veterinary Practice , C Jevring, WB Saunders and Co London. Orders Veterinary Immunology: An Introduction , 5th edn, IR Tizard, WB Saunders Co, A Division of Harcourt Brace &amp; Co Joint Disease in The Horse , CW Mcllwraith and GW Trotter Avian Medicine and Surgery , RB Altman, SL Clubb Controlled Reproduction in Sheep and Goats , Ian Gordon

Biotechnological advances in goat reproduction.

Goat selection and reproduction have resulted from using conventional methods of natural mating and artificial insemination. Genetic improvements resulting from these are usually slow. Innovative developments in biotechnology rapidly propagate superior genes, offering hope for modeling and designing animals to fit market and environmental requirements. Use of Tris, citric acid, fructose, egg yolk, and glycerol extender has enabled goat sperm to be stored successfully for several years before being used in cervical or laparoscopic insemination. Laparoscopic recovery of goat embryos to reduce adhesions from repeat surgeries has great potential in improving embryo production for direct transfer or for future transfer after cryopreservation. Goat kids have been produced, as a result of experiments to refine techniques of in vitro maturation and fertilization of recovered oocytes, with successful culture and transfer of embryos. In vitro fertilization technology is also essential for cloning goat embryos and for gene transfer. Transgenic goats have already been produced due to new genes being expressed from biologically active molecules altering the phenotype of the transferred goat. The introduced gene is capable of transmission between generations. The goat's diversified commercial value and convenient size make it a benefactor to new technology for rapid genetic improvement as a supplement to conventional selection methods.

Parametres de reproduction et de production des petits ruminants locaux au Burundi

RésuméL'étude des performances de reproduction des chèvres et des brebis burundaises réalisée en station pendant plusieurs années montre que ces deux espèces atteignent une productivité intéressante estimée à 25 et 33 kg de poids vif par an respectivement. Mais celle-ci est très réduite en milieu rural et est comprise entre 9 et 27 kg. La grande hétérogénéité des performances individuelles permet d'envisager une action de sélection rapide et efficace qui, selon les résultats enregistrés, devrait porter surtout sur les capacités laitières et la vitesse de croissance dans les deux espèces et sur la prolificité chez la brebis.