A study on the effect of GnRH administration on the ovarian response and laparoscopic intrauterine insemination of Awassi ewes treated with eCG to induce superovulation

The effect of GnRH administration on superovulatory response of ewes treated with equine chorionic gonadotrophin (eCG) in breeding and nonbreeding seasons and the contribution of laparoscopic insemination to the improvement of fertilization and embryo recovery were investigated. Twenty-four nonpregnant Awassi ewes of 3–4 years of age were randomly allocated into two groups (n = 12). Each ewe was treated with a progesterone impregnated intravaginal sponge for 12 days. The following superovulation treatment was used: ewes of group 1 received 1,200 IU of eCG once as an intramuscular injection 48 h prior to sponge withdrawal; ewes of group 2 also received 1,200 IU of eCG once as an intramuscular injection, 48 h prior to sponge withdrawal and after 24 h of sponge removal. Ewes were injected with 80 μg of GnRH. Ewes of groups 1 and 2 were further subdivided into four equal groups (n = 6). Subgroups A and C (superovulated with eCG and eCG plus GnRH, respectively) were mated naturally at least two times with Awassi rams of proven fertility at 8-h intervals. Subgroups B and D (same as A and C) had intrauterine insemination at 44–46 h after sponge removal, under laparoscopic visualization of uterine horns, depositing 1 ml of diluted semen containing 100 × 10⁶ motile sperm in the distal portion of each uterine horn. Ovarian response was assessed by determining the number of corpora lutea by laparoscopy at day 6 after mating. Embryo recovery was performed by using a semi-laparoscopic flushing procedure in both uterine horns. Results of the present study showed that ewes treated in breeding season with eCG plus GnRH has a higher number (P < 0.05) of corpora lutea than eCG alone as 7.33 ± 0.54 and 4.33 ± 0.39, respectively. There was no significant difference in the number of corpora lutea in nonbreeding season when ewes treated with eCG and eCG plus GnRH. The number of unovulated follicles was significantly higher (P < 0.05) in eCG treated ewes than in ewes treated with eCG plus GnRH, both in the breeding and nonbreeding seasons. The number of recovered embryos from ewes treated with eCG plus GnRH and eCG differ significantly (P < 0.05) as 4.32 ± 0.56 and 1.06 ± 0.26, respectively, in the breeding seasons. No significant difference was observed when these hormones used for superovulation in the nonbreeding season. A higher number of unfertilized ova (P < 0.05) was observed in ewes when naturally inseminated than in ewes inseminated using the intrauterine laparoscopic technique. Higher rate of embryo recovery (P < 0.05) was achieved when ewes were inseminated via intrauterine (4.66 ± 0.66) compared with ewes naturally mated (2.16 ± 0.74). The fertilization rate in ewes inseminated intrauterine using laparoscopic techniques and naturally mated were 91.5% and 44.8%, respectively. Fertilization failure in ewes inseminated intrauterine using laparoscopic techniques and naturally mated were 8.4% and 55.2%, respectively. It could be concluded that administration of GnRH 24 h after sponge removal increased ovulation rate of Awassi ewes treated with eCG for superovulation in the breeding season. The use of eCG to induce superovulation in Awassi ewes combined with laparoscopic intrauterine insemination increases the fertilization rate.     

Performance of three tropical hair sheep breeds.

The performance of three hair sheep breeds (Brazilian Somali, Morada Nova, and Santa Ines) was evaluated in the production environment of northeastern Brazil. Data from a total of 524 lambs sired by 21 rams and out of 190 ewes were analyzed. These data were collected from 1980 to 1983 at Sobral, Brazil from an experiment designed to compare performance of the three breeds. The traits included weights of lambs at birth, weaning, 8 mo, 10 mo, and yearling ages and ewe characters of weight at lambing (EWT), total lamb weight born (LWB), total lamb weight weaned (LWW), and prolificacy rate (PR). Differences (P < .01) among breeds were found for all characters. The Brazilian Somali, the smallest and slowest-gaining breed, was less sensitive to yearly variation than were the other breeds. The Santa Ines, the largest and fastest-gaining breed, was superior in LWB and LWW per ewe lambing. Averaged over the 4-yr period, the Morada Nova had the highest PR (1.82), and the Brazilian Somali and Santa Ines had similar PR (1.39 and 1.31, respectively). Environmental effects on PR due to yearly rainfall quantity and distribution pattern influenced lamb growth up to weaning and ewe reproduction performance. Breed x year (P < .05) interaction effects on PR were largely attributable to the Somali breed's exhibiting higher PR than the Santa Ines and Morada Nova breeds during the relatively wet years of 1981 and 1982.     

Effect of Inter‐Breed Embryo Transfer on Lamb Growing Performance and Survival

The roles of recipient and embryo genotype in determining the growth performance and survivability of offspring based on specific behavioural differences were investigated using inter‐breed embryo transfer. This study was carried out using three recipient genotypes (Awassi, Redkaraman and Tuj) and two embryo genotypes (Charollais and Romanov) to obtain the six possible combinations of ewe and lamb genotypes. Data were collected from 71 recipient ewes (10 Redkaraman with Charollais and 15 Redkaraman with Romanov embryos; 10 Tuj with Charollais and 12 Tuj with Romanov embryos, and 12 Awassi with Charollais lambs and 12 Awassi with Romanov embryos); all ewes received two frozen‐thawed embryos. Awassi ewes had a significantly longer duration of the licking/grooming event (25.5 min, p < 0.05) than Tuj ewes. Charollais lambs were significantly (p < 0.05) more likely to require birth assistance compared to Romanov lambs. Romanov lambs were significantly more (p < 0.01) active than Charollais lambs in the first 2 h after birth; ewe breed had no effect on lamb behaviour. There was no recipient breed effect on either birth or weaning weights of lambs. Charollais lambs were recorded with higher birth (5.5 ± 0.3 kg vs 3.9 ± 0.2 kg; p < 0.001) and weaning (29.4 ± 1.2 kg vs 22.4 ± 1.9 kg; p < 0.001) weights compared to Romanov lambs. At weaning Romanov lambs had significantly higher (95% vs 75%; p < 0.05) survival rates, however, this was not significantly affected by recipient breed. It was concluded that recipient breed was not an important factor in survival and weaning performance of embryo transferred lambs from a prolific breed (Romanov) while these traits recorded for lambs from meat type (Charollais) embryos were influenced by dam breed.     

Reproductive performance of postpartum ewes treated with insulin or progesterone hormones in association with ram effect

The reproductive performance of postpartum Santa Inês (SI) and Morada Nova (MN) ewes treated with insulin or progesterone hormones in association with ram effect was evaluated. Ewes from SI (n = 69) and MN (n = 69) breeds were randomly allocated to three groups of each breed (T1—ram effect only; T2—ram effect + insulin; T3—ram effect + progesterone). Progesterone concentrations (ηg/ml; mean ± SD) before and after introduction of rams (n = 6) were 0.51 ± 0.22 and 3.78 ± 0.68 (T1), 0.65 ± 0.21 and 3.77 ± 0.78 (T2) and 0.52 ± 0.21 and 3.84 ± 0.84 (T3) in SI ewes and 0.74 ± 0.19 and 3.71 ± 0.56 (T1), 0.70 ± 0.21 and 3.79 ± 0.75 (T2) and 0.81 ± 0.14 and 3.87 ± 0.80 (T3) in MN ewes, respectively. Thus, lower progesterone concentrations were found before the introduction of rams (p < .05). After the introduction of rams, preovulatory peaks of LH (ηg/ml) occurred at 28 (T1), 44 (T2) and 48 (T3) hr in SI ewes and at 64 (T1), 40 (T2) and 44 (T3) hr in MN ewes. The mean number of ovulations was similar between groups (p > .05), was 1.3 ± 0.51 (T1), 1.5 ± 0.54 (T2) and 1.6 ± 0.51 (T3) in SI ewes and 1.3 ± 0.51 (T1), 1.6 ± 0.51 (T2) and 1.6 ± 0.51 (T3) in MN ewes. In conclusion, the ram effect alone is effective at inducing and synchronizing oestrus in sheep under postpartum anoestrus, irrespective of hormone treatments.     

Multiple Factors Affecting Superovulation in Poll Dorset in China

To expand the breeding flock of Poll Dorset sheep in China, multiple ovulation and embryo transfer breeding program was applied to the limited number of imported Australian Poll Dorset sheep. This study investigated the effects of FSH from three different manufacturers, parity (nulliparous vs multiparous), repeated superovulation, oestrus induction, corpus luteum regression and oestrus delay on Poll Dorset superovulation. The results showed that gonadotropin FSH from Canada Folltropin‐V (Ca‐FSH) was successfully used for superovulatory treatment with 160 mg–200 mg dosage per ewe and recovered 12.91 ± 7.80 embryos. Multiparous ewes for superovulation treatment were significantly better nulliparous ewes (p < 0.05). The successive superovalution treatment reduced significantly embryo collection but did not affect transferable embryo number. Ewes with natural oestrus resulted in significantly higher number of embryos (13.83 ± 4.64) and of transferable embryos (12.00 ± 5.76) than ewes with induced oestrus (7.00 ± 4.92; 4.22 ± 3.42) and unknown oestrus cycle (5.94 ± 3.38; 3.19 ± 2.56, p < 0.05). The delayed oestrus ewes at 24 h after superovulatory treatment produced significantly fewer embryos and transferable embryos (0.92 ± 1.51 vs 0.42 ± 0.90) than those with normal oestrus (p < 0.01). Furthermore, the more transferable embryos were recovered from ewes with normal corpus luteum than those with corpus luteum regression (5.88 ± 5.09 vs 3.59 ± 4.30 and 8.83 ± 5.75 vs. 6.66 ± 5.41, p < 0.01). These results suggest that in our farm practice, a comprehensive treatment method by using the Canadian FSH (Folltropin‐V), plus choosing multiparous and natural oestrus ewes with normal corpus luteum might obtain an optimum embryo collection and embryos transfer in sheep.     

Estrus synchronization in sheep with synthetic progestagens

Sixteen female sheep of Degua breed were assigned to receive either the full dose of norgestomet ear implant and injectable solution containing norgestomet and estradiol valerate (n = 8) or half the dose (n = 8). The ear implants were removed in both groups on day 12. All ewes received an intramuscular administration of 500 IU PMSG at implant withdrawal. Synchronized ewes were individually hand mated twice at 48 and 60 hours after implant removal. One ewe in each group however refused mating on both occasions. Pregnancy diagnosis was conducted by bimanual external palpation 90 to 100 days post mating. The conception rates (3/7, 42.85%) and (5/7, 71.42%) were recorded in the two treatment groups, respectively. All eight ewes lambed between 145 to 153 days post mating. In group I ewes carried only singletons (prolificity rate 1.0) whereas in group II two ewes delivered twins, producing 7 lambs with prolificity rate of 1.4 (N.S). From this preliminary investigation it appears that the lower dose of norgestomet ear implants offers better option for estrus synchronization accompanied by higher fertility.     

Mineral requirements for weight gain in growing male Santa Inês and Morada Nova hair sheep

This study estimated the net macro and micromineral requirement from the 48 male uncastrated lambs (24 growing male Santa Inês and 24 growing male Morada Nova hair sheep), with initial weights of 21.7 ± 1.2 kg and 20.8 ± 0.8 kg using the comparative slaughter method. The experimental diet consisted of 30% forage (Buffel—Cenchrus ciliaris (L) hay) and 70% concentrate (corn grain 43.5%, soybean meal 22.0%, vegetable oil 3.0% and mineral supplement 1.5%). The experimental design was a completely randomized with two breeds, four weights, and six replicate. Mineral requirements sufficient to promote weight gain in Santa Inês sheep ranged from 1.75 to 1.03 g Ca, 1.01 to 0.61 g of P, 0.38 to 0.21 g of K, 0.38 to 0.16 of Na, 0.10 to 0.06 Mg, 28.5 to 16.0 mg of Fe, 6.14 to 3.22 mg of Cu, and Zn 23.0 to 14.0 mg/kg per unit of empty body weight (EBW) gain. In the Morada Nova breed, the requirements ranged from 1.96 to 0.84 g of Ca, 1.15 to 0.46 of P, 0.39 to 0.19 of K, 0.28 to 0.13 of Na, 0.10 to 0.05 Mg, 26.2 to 12.9 mg of Fe, 5.59 to 2.46 Cu, and Zn 23.6 to 10.3 mg/kg of EBW gain. Mineral requirements varied mainly in accordance with the proportion of bone mass and fat concentration in the carcass, which were influenced by the slaughter weight of the animals, and therefore should be used in the formulation of dietary mineral supplements.     

Environmental factors and interval from the introduction of rams to estrus in postpartum Saint Croix sheep

The objective of this study was to determine whether season and total rainfall during the breeding season, sheep parity, and/or litter size affect the interval from the introduction of rams to estrus (IRE) in hair Saint Croix sheep in northeastern Mexico. An analysis was made of 874 services performed during 9 years, introducing the rams into the sheep flock after an isolation period of 60 days during the postpartum period. Estrus was recorded twice daily during 35 days. Year and season influenced significantly on the interval between ram introduction and estrus length (P < 0.01). Winter IRE length (7.9 ± 0.1 days) was shorter than in the other three seasons (11.1 ± 0.2, 11.1 ± 0.1, and 16.2 ± 0.2 days in summer, autumn, and spring, respectively) (P < 0.01). An interaction was observed between rainfall and season, then by rainfall between 0 and 100 mm, IRE was shorter (P < 0.05) in winter (6.8 ± 0.3 days), and by rainfall between 100 and 199 mm, IRE was shorter (P < 0.05) in autumn (10.2 ± 0.5 days); however, when rainfall was beyond 200 mm, IRE length was shorter (P < 0.01) in summer (4.8 ± 0.5 days) than in autumn (14.5 ± 0.3 days). The IRE length was also longer in first lambing ewes (P < 0.05) and was not affected by litter size. In the present study, several factors, including the breeding season, rainfall and parity, directly influenced the interval between the male introduction and the onset of estrus by Saint Croix hair sheep.     

Awassi sheep reproduction and milk production: review

Awassi is the local breed of sheep in Jordan and is the most important breed in the semi-arid regions of the near east countries. Awassi ram and ewe lambs reach puberty at around 8 and 9 months of age, respectively. The breeding season of Awassi ewes starts as early as April and lasts through September. After puberty, Awassi rams are sexually active throughout the year. The normal estrous cycle in Awassi ewes is 15–20 days (average 17 days). Estrus ranges from 16–59 h (average 29 h) during the breeding season. The reproductive performance of unimproved Awassi sheep has been low while improved Awassi has the highest fertility and milk production and are the heaviest among all Awassi populations. The gestation length varies from 149 to 155 days (average 152 days). Hormones that are commonly used for induction and synchronization of estrus in Awassi ewes include progestins, gonadotropins and PGF2α. An Awassi ewe produces 40–60 and 70–80 kg of milk per 150-day lactation period under traditional and improved production systems, respectively, in addition to the suckled milk left for lambs until weaning. The improved Awassi has the highest milk production among all Awassi populations and may reach 506 L over 214-day lactation period. The objective of this review is to summarize the reproductive pattern and milk production of Awassi sheep in the Middle East region.     

Do traditional sheep breeders perform conscious selection? An example from a participatory breeding program of Morada Nova sheep

The implementation of sustainable breeding programs requires genetic breeding strategies that are appropriate for the reality production systems. It is also essential that the choice of animal selection criteria be based on breeders’ knowledge and objectives. This work is an ethno-zootechnical study of the Morada Nova sheep breed and its crossbreeds. The goals of this study were to register and analyze indigenous breeders’ knowledge and practices regarding animal selection criteria and to generate technical information to support a participatory breeding program of the breed. This study was conducted in the Morada Nova municipality in the state of Ceará, Brazil. Semi-structured interviews were evaluated using two groups of individuals, purebred Morada Nova sheep breeders (RMN, n = 13) and breeders of Morada Nova crossbreeds (MMN, n = 48). Interview questions were used to identify local selection criteria adopted by each group in the choice of animals for breeding. Data from the interviews were submitted to frequency distribution analysis and the Shapiro-Wilk test to verify their distribution. Later, the Kruskal-Wallis test was used to compare the two groups of farmers based on that information, in addition to multivariate statistical analysis and evaluation of Smith salience index. Breeders in the RMN group used selection criteria related to breed standards, such as pelage color. In contrast, breeders of the MMN group used criteria related to productivity, such as body conformation and milk production. Breeders should be engaged in the development of breeding programs, and it is important to consider their preferences and objectives when evaluating breeding animals.     

A mail survey of factors affecting performance in 627 selected sheep flocks in south-eastern Norway

Abstract

Factors influencing rate of barren ewes, number of lambs born per pregnant ewe, and autumn live weight of the lambs were studied in 627 Norwegian sheep flocks based on herd level data from the Norwegian Sheep Recording System and a mailed questionnaire to the sheep farmers. The following factors were significantly associated (P<0.05) with rate of barren ewes: breed, herd average lambing date, type of production/age of farmer, routines for treatments for parasites, and housing type. Number of lambs born per pregnant ewe was significantly associated with rate of barren ewes, herd average lambing date, breed, percentage grass silage of total roughage, and no separation of gimmers during the housing period. Corrected autumn live weight of the lambs was significantly associated with breed, flock size, lambs born per pregnant ewe, no separation of gimmers during the housing period, and type of summer pasture.     

Performance and carcass measurements of ewe lambs reared in a feedlot and fed wheat (<Emphasis Type="BoldItalic">Triticum durum</Emphasis> Desf.) middlings total mixed rations in the summer season

The effect of total mixed ratios containing wheat middlings (WM) as a corn grain substitute on the growth performance and carcass traits of Comisana ewe lambs was evaluated. Forty ewe lambs, with average live body weight of 13 ± 0.3 kg (mean ± SEM), were allocated randomly to two isocaloric and isonitrogenous diets for 50 days. Control diet contained 400 g/kg of dry matter (DM) of corn as the main starchy source, whereas experimental diet contained 600 g/kg DM of WM. In vivo nutrient apparent digestibility of the two diets was determined using Comisana rams (mean body weight, 65 ± 2.3 kg) and indicated significant (P < 0.05) differences for neutral detergent fibre, acid detergent fibre, cellulose and hemicellulose fractions. Results from the trial using Comisana ewe lambs showed that growth traits were unaffected by dietary treatments as well as none of the carcass measurements examined (P > 0.05). These findings indicate that WM results as a suitable feed ingredient for growing ewe lambs that can be a satisfactory substitute to conventional grain source.     

Analysis of size and conformation of native Creole goat breeds and crossbreds used in smallholder agrosilvopastoral systems in Puebla,Mexico

Liveweight (LW) of does and bucks of the native Creole goat breed and crosses of Creole does and Nubian bucks, aged 1.5–5 years, were recorded and body traits including: head length (HL), head width (HW), body length (BL), trunk length (TL), chest girth (CG), abdominal perimeter (AP), rump length (RL), and height at withers (HW) were measured to develop equations for predicting LW from the body measurements. Weight, sex, breed and kidding date of 354 kids were recorded at birth, and LW of the kids was measured monthly for one year to determine the effect of kidding season on growth rate. Bucks had higher (p < 0.05) body measurements than the does (HL 15.1 ± 0.1 vs 16.6 ± 0.2 cm; BL 97.6 ± 0.4 vs 104.6 ± 1.2 cm; CG 78.8 ± 0.4 vs 79.9 ± 1.0 cm; AP 82.4 ± 0.5 vs 87.2 ± 1.1 cm; HW 62.7 ± 0.4 vs 70.1 ± 0.8 cm). With the exception of TL, F₂ does had higher (p < 0.05) body measurements and LW (28.8 ± 1.5 vs 27.7 ± 0.5 kg) than Creole does. The body traits of the F₁ does were similar (p > 0.05) to those of Creole does with the exception of HL, BL and HR. The F₂ kids were heavier (p < 0.05) at birth (3.31 ± 0.1 vs 2.60 ± 0.1 kg) and grew faster than the Creole kids. Male kids were heavier (p < 0.05) at birth (3.21 ± 0.10 vs 2.73 ± 0.13 kg), and grew faster than female kids. Season had a significant effect on birth weight. The results showed that LW of Creole goats and Creole × Nubian does could be estimated in the field using body traits. Birth weight and growth rate of kids could be improved by management practices that affect season of kidding.     

Human–animal interaction,stress, and embryo production in <Emphasis Type="Italic">Bos indicus</Emphasis> embryo donors under tropical conditions

This study investigated the effect of human–animal interaction (HAI) and the stress response on the quality of embryo production in superovulated Nelore (Bos indicus) cattle, under tropical conditions. Thirty-two females underwent a superovulation protocol for 5 days. Cortisol concentrations were determined in blood plasma collected on days 0, 4, and 5. Artificial insemination was performed on days 4 and 5, and nonsurgical embryo flushing on day 11. Embryo production and viability were determined. Human stimulation, animal behaviors, accidents, and handling time were recorded to assess HAI. Cattle age was negatively correlated with accidents, frequency of aversive behaviors, and negative stimuli by stockperson during transit through corral compartments to receive superovulation treatments. The factor analysis revealed two distinct groups. The first group was called stressed and had higher cortisol concentration than the nonstressed group, 16.0 ± 2.1 and 12.5 ± 1.0 ng/mL, respectively. Comparisons between these groups showed that the frequency of voice emissions by the stockperson and the number of accidents were higher in the stressed group, and also, the mean handling time was longer in the stressed group than for the nonstressed. As a result, viability rate of the embryos was 19% lower in the stressed group (P < 0.05). This indicates that intensive negative HAI is likely related to stress, which affects embryo production in a superovulation program.     

The epidemiology of paramphistomosis of sheep (<Emphasis Type="Italic">Ovis aries</Emphasis> L.) in the north west temperate Himalayan region of India

An epidemiological study with the objective to assess the prevalence of paramphistomosis in association with season, age, sex and breed was carried out in naturally infected sheep over a period of two years from February 2005 to January 2007. Gastrointestinal tract (GIT) and faecal examination were conducted monthly to monitor the seasonal occurrence of paramphistomosis. 793 sheep were examined in the first year, out of which 7.06% were positive for Paramphistomum infection. In the second year, 740 animals were investigated and 7.7% were infected. The overall prevalence of paramphistomosis was 7.3% with a mean of 56.50 ± 0.50 and 95% confidence interval (CI) (lower bound: 50.1469; upper bound: 62.8531). The prevalence of paramphistomosis through GIT examination (P = 0.593) was 7.6% at 95% CI (lower bound: −19.1186; upper bound: 57.1186) and the prevalence through faecal examination (P = 0.884) was 7.2% at 95% CI (lower bound: 5.7345; upper bound: 69.2655). Generally, season and age were the factors found to have a significant influence on the risk of paramphistomosis in sheep. The highest infection was found in the summer season (P < 0.005); lower age groups (P < 0.005) in males and in migratory (Bhakarwal) breed (P ≥ 0.005). Winter, adult animals, females and local breed reported low infection. The present study will be of great significance to understand the epidemiology of gastrointestinal helminthes of sheep initially in the resource poor communities of Himalayan region and will definitely be helpful to devise appropriate control strategies for paramphistomosis.     

Effect of semen and donor factors on multiple ovulation and embryo transfer (MOET) in sheep

Multiple ovulation and embryo transfer (MOET) is an important tool in the sheep industry for increasing numbers of genetically superior individuals. The objective of this study was to evaluate the effect of semen source (frozen or fresh), the number of embryo collection procedures for each donor (NECP), the season in which embryo transfer and collection was performed, and the age and breed of the donor, on the number of recovered embryos and pregnancy rates after embryo transfer. The Alamos Genetics’ flushing station database was used. This consisted of 140 embryo collection procedures, from 53 Dorper and White Dorper sheep donors, aged between one and eight years, totalling 1,200 collected embryos. Neither the number of retrieved embryos nor the pregnancy rate was affected by the semen preservation method (fresh or frozen), NECP or the age and breed of donor. The season did not affect the number of collected embryos but had a significant effect (p < 0.05) on the recipient pregnancy rate, with higher pregnancy rates reported in the winter (65.57% ± 25.33%) compared with spring (37.11% ± 33.27%), summer (29.95% ± 28.33%) or autumn (35.03% ± 31.66%). There is an estimated increase of 98.4% and 71.5% of embryos recovered in the spring and summer seasons, respectively, when winter is used as reference. The survival of embryos is significantly higher when implanted during the breeding season, more specifically in winter. Embryo collection can be carried out throughout the year in sheep, but there may be a marginal advantage in the use of superovulation and fresh embryo transfer programmes in the autumn and winter.     

Milk yield estimation of Ogaden cattle breed based on methods of weigh–suckle–weigh and calves’ growth

Daily milk yield of Ogaden cattle was estimated from milk suckled by 269 calves born and maintained between 1994 and 2004 at Haramaya University Beef Farm, Ethiopia. The weigh–suckle–weigh method and the growth of calves were used to estimate the yield. Mean predicted daily milk yield of the breed based on the weigh–suckle–weigh method was 4.39 ± 0.03 kg day⁻¹. Daily milk yield estimated from the growth of calves up to 3 months of age was 4.59 ± 1.43 kg day⁻¹. The milk yield was significantly affected by seasons of calving (p < 0.001), parities of the dams (p < 0.05), weeks of lactation (p < 0.001) and birth weights of calves (p < 0.05). A relatively higher milk yield was observed from cows calved during the long rain season. A higher milk yield was produced by cows in fifth parity. Heavier calves at birth suckled more milk than lighter calves. Daily milk yield was significantly higher in 3–6 weeks of lactation. The result of this study indicated that the milk yield produced by Ogaden breed was relatively higher than the yield of some Zebu breed measured by partial suckling system in Ethiopia and was comparable to the yield from Zebu cattle in the tropics estimated by the same method.     

Mutations in bone morphogenetic protein 15 and growth differentiation factor 9 genes are associated with increased litter size in fat-tailed sheep breeds

The objective of this study was to investigate association between GDF9 and BMP15 gene polymorphism and litter size in fat-tailed sheep, a total of 97 mature ewes from four breeds (Afshari=19; Baluchi=18; Makui=30 and Mehraban=30) were genotyped for the BMP15 HinfI and GDF9 HhaI polymorphisms by PCR-RFLP technique. The highest and lowest mutant allele frequencies were found in Makui (0.27) and Afshari (0.10) sheep for the BMP15 gene and in Afshari (0.24) and Mehraban (0.18) sheep for the GDF9 gene, respectively. Litter size was significantly influenced by genotype of the ewe for two genes (P < 0.01). Heterozygous genotypes for both loci showed higher litter size than homozygous genotypes (P < 0.01). None of the individuals carried homozygous genotype for both of the GDF9 and BMP15 variants in these breeds. The individuals carrying the mutant allele for one of the investigated candidate gene still showed fertile phenotype. Thus, existence of homozygosity at one of the BMP15 and GDF9 variant is not probably able to block normal hormonal pathway of reproduction in fat-tailed sheep.     

Effect of tropical browse leaves supplementation on rumen enzymes of sheep and goats fed <Emphasis Type="Italic">Dichanthium annulatum</Emphasis> grass-based diets

In a switch-over experiment, eight male animals, four each of sheep and goats of local breeds with mean body weight of 26. 8 ± 2.0 and 30.0 ± 2.1 kg, were fed Dichanthium annulatum (DA) grass and four browse species viz. Helictris isora, Securengia virosa, Leucaena leucocephala (LL) and Hardwickia binnata (HB) in four feeding trials to assess their supplementary effect on activity of rumen enzymes. The sheep and goats were offered DA grass with individual browse in 75:25 and 50:50 proportions, respectively, for more than 3 months during each feeding trial, and rumen liquor samples were collected twice at 0 and 4 h post feeding after 60 and 90 days of feeding. Glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT) and glutamate dehydrogenase (GDH) enzymes were determined in the bacteria and protozoa fractions of rumen liquor, while cellulase enzyme activity was measured in mixed rumen liquor. LL and HB had the highest and lowest contents of CP, while fibre contents were lower in early than later browse leaves. Supplementation of browse leaves significantly (P < 0.05) affect the specific activity of GDH enzyme in bacteria fraction of rumen liquor of animal species, while GDH activity was similar in protozoa fraction of rumen liquor of sheep and goats on all DA grass–browse-supplemented diets except DA–HB (42.8 units/mg protein), where activity was significantly (P < 0.05) low. Specific activities of GOT and GPT enzymes in both bacteria and protozoa fractions of rumen liquor differ significantly (P < 0.05) due to supplementation of browse leaves to DA grass. Browse leaves significantly (P < 0.05) affect the cellulase enzyme activity in animal rumen liquor, being highest on DA–LL (193.4) and lowest on DA–HB diet (144.8 μg sugar/mg protein). Goat exhibited higher activities of GOT and GPT than sheep in both bacteria and protozoa fraction of rumen liquor, while cellulase activity was similar between the animal species on the grass–browse leaves diets. Results indicate that browse leaves supplementation affect the enzyme activities of sheep and goats rumen, while the goats rumen liquor had higher activities of GOT, GPT and GDH enzyme than sheep.     

Comparison of Booroola Merino and Finnsheep: effects on productivity of mates and performance of crossbred lambs

Booroola Merino (BM) and Finnsheep (FS) rams were mated to FS and crossbred (CO) ewes to compare their effects on the productivity of their mates and the performance of their progeny. Effects of breed of ram and the interaction of breed of ram X breed of ewe were no significant for fertility, total number born, number born alive, litter birth weight, or number of lambs weaned by the ewe or in the nursery. Birth weights of FS- and BM-sired lambs were equal, but FS-sired lambs were heavier at weaning and 147 d of age. Compared with BM-sired lambs, survival from birth to weaning of dam-reared lambs was greater for FS-sired lambs produced by CO dams than for FS-sired lambs produced by FS dams. At a constant live weight, FS-sired lambs had a heavier carcass with less external fat thickness than BM-sired lambs. Percentage of ewe lambs reaching puberty was lowest and age at puberty was highest for the BM X CO cross; relatively small differences existed between the other three genotypes for these traits. Ewe lambs sired by BM had a greater ovulation rate than FS-sired ewe lambs. Embryo mortality was greater in BM X CO ewe lambs than in ewe lambs of the other three genotypes; the difference was larger for ewes with three ovulations than for ewes with two ovulations. The net result was that BM X CO ewe lambs averaged slightly fewer lambs born than FS X CO ewes. The BM X FS ewe lambs had larger litters than the FS ewes due to a substantially higher ovulation rate and only a slightly lower overall embryo survival rate. With the exception of ovulation rate and litter size, FS rams produced lambs with a more desirable level of performance than did BM rams.