Ewe Parity Research Articles

Survival analysis of genetic and non-genetic factors influencing ewe longevity and lamb survival of Ethiopian sheep breeds

Survival analysis applying proportional hazards models was used to investigate genetic and non-genetic factors affecting ewe longevity and lamb survival of sheep in Ethiopia. Data were obtained from an on-station closed nucleus breeding program of Menz sheep and an on-farm Awassi×Menz sheep crossbreeding project. A total of 695 ewes and 1890 lambs born from the nucleus population of Menz sheep were used for the analysis of ewe productive life and lamb survival to yearling age respectively. In addition, 5530 lamb records of purebred local and crossbreds with proportions of ~25–50% Awassi, collected from three locations were used for the analysis of lamb survival from birth to weaning age. The effects of year, ewe parity and litter weight at weaning were significant (p<0.05) for ewe productive life. On-station lamb survival to yearling was affected by year and breeding value of yearling weight of the lamb, indicating that faster growing animals had substantially higher survival rates. Animal model heritability estimates for lamb mortality ranged from 0.02 to 0.10. While there was a strong genetic trend for growth rate, as evidenced by estimated breeding values for different birth years, estimated breeding values for lamb survival were variable across years with decreasing trend. These results indicate no antagonism between growth rate and survival under conditions prevailing in the nucleus system. Routine genetic evaluation for survival is suggested. Under farmer conditions, the effects of year, season, sex and location effects were significant (p<0.05) on lamb survival to weaning age whereas breed composition (local versus crossbred) of dam as well as of the lamb were not significant. This seems to indicate that crossbreeding of local animals with Awassi sheep does not have an adverse effect on the survival of lambs under farmer conditions typical for the Ethiopian highland regions included in this study.

Pen size and parity effects on maternal behaviour of Small-Tail Han sheep

The aim of this experiment was to study the effects of pen size and parity on maternal behaviour of twin-bearing Small-Tail Han ewes. A total of 24 ewes were allocated to a 2×2 design (six per pen), with parity (primiparous or multiparous) and pen size (large: 6.0×3.0 m; small: 6.0×1.5 m) as main effects at Linyi University, Shandong Province, China. Behaviour was observed from after parturition until weaning. All ewes were observed for 6 h every 5 days from 0700 to1000 h and from 1400 to 1700 h. Continuous focal animal sampling was used to quantify the duration of maternal behaviours: sucking, grooming and following as well as the frequency of udder accepting, udder refusing and low-pitched bleating. Oestradiol and cortisol concentrations in the faeces (collected in the morning every 5 days) were detected using EIA kits. All lambs were weighed 24 h after parturition and again at weaning at 35 days of age. The small pen size significantly reduced following (P<0.005), grooming (P<0.001) and suckling durations (P<0.05), as well as the frequency of udder refusals (P<0.001). However, there was a significant interaction with ewe parity, with decreased grooming and suckling in the small pen largely seen in the multiparous ewes (P<0.001). Independent of pen size, multiparous ewes accepted more sucking attempts by their lambs (P<0.05) and made more low-pitched bleats than primiparous ewes (P<0.001). Multiparous ewes had higher faecal oestradiol concentrations than primiparous ewes (P<0.001), and ewes in small pens had higher faecal cortisol levels compared with ewes in larger pens (P<0.001). As lambs increased in age, the duration of maternal grooming, following and suckling as well as frequency of udder acceptance and low-pitched bleating all declined, and the frequency of udder refusing increased (P<0.001 for all). Ewe parity, but not pen size, affected lamb weight gain during the period of observation (P<0.001). This is the first study to show that pen size, interacting with parity, can affect the expression of maternal behaviour in sheep during lactation. The study is also the first to report on the maternal behaviour of Chinese native sheep breeds (Small-Tail Han sheep), with implications for the production of sheep in China.

Parity : A Selection Criteria for Pre-Weaning Morphometric Traits of West African Dwarfsheep = أعداد الولادات : معايير الانتخاب للصفات الشكلية قبل الفطام في سلالة خراف الدورف الغرب إفريقي

One hundred and seventy six lambs produced by 84 ewes in their first to seventh parity were used to determine the effect of the number of births of ewe on the pre-weaning morpho metric traits of West African dwarf lambs. Body weight (BW), body length (BL), heart girth (HG) and height at wither (HW), were taken at birth, 4, 8 and 12 weeks after birth. Pre-weaning morpho metric traits of the lambs were significantly (P<0.05) affected by the parity of the ewe. The heaviest birth weight was recorded for lambs produced by fifth-parity ewes while the lambs from first parity had the least value. The highest value of BW, BL, and HW (4.74 ± 0.07kg, 37.00 ± 1.18cm, 41.32 ± 0.23cm) and (6.47 ± 0.09 kg, 40.40 ± 0.81cm, 46.11 ± 0.54 cm) were recorded from ewes in their fifth parity at weeks 4 and 8; respectively. Lambs produced by sixth parity ewes had the highest value of HG (39.00 ± 0.32cm, 42.01 ± 0.16 cm, and 42.80 ±0.86 cm) at birth, and 4 and 8 weeks after birth; respectively. However, the effect of parity on the growth performance tended to disappear at week 12. Sexual dimorphism was observed on all the morpho metric traits at week 12 in favour of male lambs. Growth performance of the lambs increases with parity though the effect was less significant at weaning.

Effect of selected factors on basic reproduction, growth and carcass traits and meat production in Texel sheep

The objective of this work was to determine the effect of lambing year, sire effect, parity of ewes’ lambing (PL) and gender on selected indicators of meat production and fertility in a Texel sheep herd. The evaluation proceeded for a period of 5 years, when 356 ewe – lambs and 321 Texel ram – lambs were monitored. Processing of the data set was done by the SAS program, GLM procedure. The lambing year had a significant effect (P &lt; 0.05; 0.01) on all indicators observed except litter size. The sire effect was found to be significantly (P &lt; 0.05; 0.01) related to all indicators monitored. The significant differences (P &lt; 0.01) were found in fat thickness and lambs’ muscularity. The frequency of lambs’ gender was not significantly affected by the litter size and number of lambs weaned. Lambs’ gender affected the MLLT depth of lambs nonsignificantly. Litter size, as well as the number of weaned lambs, increased with the higher PL (1.44 with primiparas, 2.17 with ewes at the 5th and subsequent lambings, P &lt; 0.01; resp. 1.31 with primiparas, 2.01 with ewes at the 5th and subsequent lambings, P &lt; 0.01). The live weight at 100 days of age was significantly lower in lambs from the 5th and following litters, as well as the daily gain from birth till 100 days of age (DG 100) and MLLT depth in comparison to the 2nd, 3rd and 4th litters (P &lt; 0.05). On the average, ram – lambs reached a higher live weight at 100 days of age (+1.79 kg, P &lt; 0.01), and DG 100 in contrast to female (+17.22 g, P &lt; 0.01).

A Comparative Performance Study between Afec-Awassi Crossbred , Improved Awassi and Local Awassi Sheep Reared Intensively in Jordan

A total of 246 performance and 257 prolificacy records belong to Afec-Awassi crossbred, improved and local Awassi sheep were collected through the years from 2007 to 2010. The sheep were kept under intensive production system at Al-Khanasry Research Station in the North of Jordan. The studied traits were: milk production, lactation, period, milk composition, birth weight and prolificacy of ewes of the three lines. The following environmental effects, parity of ewe, type of birth, sex of lambs and body weight of ewe at lambing were studied. The results showed that sex of lamb’s effect was significant in which males were heavier (P≤0.05) than females. Single born lambs were heavier (P ≤ 0.05) than other types of birth. Effect of ewe body weight at lambing on prolificacy was negatively significant (P≤ 0.01). Birth weight of Afec-Awassi crossbred lambs and the ewes' prolificacy were significantly higher than the lambs of other two lines. Year and ewe parity had significant effect on total milk production and lactation period. Total milk production was the highest (P < 0.05) in Improved Awassi ewes (134.1 ±15. 5 kg) with average lactation period of 106.2 ± 8 days, while the lowest lactation period was obtained by Afec Awassi ewes (83.3 ± 7 d). Fat and protein contents did not significantly differ between the studied lines. In conclusion, the fecundity gene that introduced into the Awassi sheep might have a remarkable positive effect on prolificacy, while it may contribute negatively in milk production.

Maternal dietary intake alters organ mass and endocrine and metabolic profiles in pregnant ewe lambs

To determine the impacts of Se supply and maternal dietary intake on ewe organ mass and endocrine and metabolic changes throughout gestation, pregnant first parity ewes (n=77) were allocated to 6 treatments in a 2×3 factorial array. Factors included Se [adequate Se (ASe; 9.5μg/kg BW) vs. high Se (HSe; 81.8μg/kg BW)] initiated at breeding and dietary intake [60% (RES), 100% (CON), or 140% (EXC) of requirements] initiated on d 50 of gestation. Ewes were individually fed and blood samples from the jugular vein were obtained approximately every 14 d from d 50 until parturition. Maternal Se supply did not impact endocrine or metabolic status. There was a nutritional intake by day interaction for NEFA, blood urea nitrogen (BUN), insulin, triiodothyronine (T3), thyroxine (T4), progesterone (P4), and estradiol-17β (E2). As expected, with increased maternal intake, NEFA concentrations were reduced. During the last weeks of gestation, BUN and insulin were elevated in EXC compared with RES ewes. Although the pattern of T3 and T4 differed throughout gestation within a treatment group, as maternal intake increased, circulating T3 and T4 were increased. For P4 and E2, as maternal dietary intake increased, there was a reduction in the steroid concentrations in jugular blood. There was only a main effect of maternal nutrition (P<0.001) for cortisol concentrations with EXC ewes having greater concentrations than RES and CON ewes, which did not differ. Although Se is known to influence thyroid hormone metabolism, supranutritional levels during pregnancy did not alter circulating T3 and T4 concentrations. Alterations in maternal endocrine status may have influenced placental transport of nutrients to the developing fetus, which we have shown previously is affected by maternal dietary Se and intake. In addition, the alterations in mammary gland weight that we observed may explain the impact of maternal nutrition on mammary gland function and colostrum production, thereby further impairing growth of developing neonates.

Diagnostic value of cytokeratin 19, HBME-1, and galectin-3 immunostaining of cell block from fine-needle aspiration specimens in papillary carcinoma of the thyroid

This study determined the energy content and immunoglobulin G (IgG) concentration of Awassi ewe colostrum and examined the effects of parity and litter size on them. Colostral samples were collected from 57 ewes from the 1st to 7th parities with a litter size of 1 or 2, within 12 h after lambing. Concentrations of colostral fat, lactose, and protein were measured as energy sources, and IgG was measured as representative of the immunoglobulin content of the colostrum. Mean values obtained from analyses of the ewe colostrum samples were 7.4 ± 2.1 kJ/g for the energy value and 60.9 ± 21.4 mg/mL for IgG. Ewe parity did not influence colostral energy content, whereas the IgG concentration of the colostrum obtained from the primiparous ewes was higher than that from the multiparous ewes (P < 0.05). Among the multiparous ewes, the colostrum obtained from ewes carrying twins showed higher energy content and IgG concentrations than that from those carrying a single lamb (P < 0.05).

Effects of parity and litter size on the energy contents and immunoglobulin G concentrations of Awassi ewe colostrum

This study determined the energy content and immunoglobulin G (IgG) concentration of Awassi ewe colostrum and examined the effects of parity and litter size on them. Colostral samples were collected from 57 ewes from the 1st to 7th parities with a litter size of 1 or 2, within 12 h after lambing. Concentrations of colostral fat, lactose, and protein were measured as energy sources, and IgG was measured as representative of the immunoglobulin content of the colostrum. Mean values obtained from analyses of the ewe colostrum samples were 7.4 ± 2.1 kJ/g for the energy value and 60.9 ± 21.4 mg/mL for IgG. Ewe parity did not influence colostral energy content, whereas the IgG concentration of the colostrum obtained from the primiparous ewes was higher than that from the multiparous ewes (P < 0.05). Among the multiparous ewes, the colostrum obtained from ewes carrying twins showed higher energy content and IgG concentrations than that from those carrying a single lamb (P < 0.05).

Nutritional plane and selenium supply during gestation affect yield and nutrient composition of colostrum and milk in primiparous ewes1

The objectives were to investigate effects of nutritional plane and Se supply during gestation on yield and nutrient composition of colostrum and milk in first parity ewes. Rambouillet ewe lambs (n = 84, age = 240 ± 17 d, BW = 52.1 ± 6.2 kg) were allocated to 6 treatments in a 2 × 3 factorial array. Factors included Se [adequate Se (ASe, 11.5 µg/kg of BW) or high Se (HSe, 77.0 µg/kg of BW)] initiated at breeding, and nutritional plane [60 (RES), 100 (CON), or 140% (HIH) of requirements] initiated at d 40 of gestation. Ewes were fed individually from d 40, and lambs were removed at parturition. Colostrum was milked from all ewes at 3 h postpartum, and one-half of the ewes (n = 42) were transitioned to a common diet meeting lactation requirements and mechanically milked for 20 d. Colostrum yield was greater (P = 0.02) for HSe ewes than ASe, whereas CON had greater (P < 0.05) colostrum yield than RES and HIH. Colostrum Se (%) was greater (P < 0.01) for HSe than ASe. Colostrum from ewes fed HSe had less (P = 0.03) butterfat (%), but greater (P ≤ 0.05) total butterfat, solids-not-fat, lactose, protein, milk urea N, and Se than ASe. Colostrum from HIH ewes had greater (P ≤ 0.02) solids-not-fat (%) than RES, whereas RES had greater (P ≤ 0.04) butterfat (%) than CON and HIH. Colostrum from ewes fed the CON diet had greater (P = 0.01) total butterfat than HIH. Total solids-not-fat, lactose, and protein were greater (P < 0.05) in colostrum from CON than RES and HIH. Ewes fed HSe had greater (P < 0.01) milk yield (g/d and mL/d) than ASe, and CON and HIH had greater (P < 0.01) yield than RES. Milk protein (%) was greater (P ≤ 0.01) in RES compared with CON or HIH. Ewes fed HSe had greater (P < 0.01) milk Se (µg/g and mg/d) than ASe on each sampling day. Milk from CON and HIH ewes had greater (P < 0.01) total solids-not-fat, lactose, protein, and milk urea N than RES. Total Se was greater (P = 0.02) in milk from ewes fed the CON diet compared with RES. Somatic cell count and total somatic cells were greater (P ≤ 0.05) in milk from CON than RES. A cubic effect of day (P ≥ 0.01) was observed for milk yield (g and mL). Butterfat, solids-not-fat, lactose, milk urea N, and Se concentration responded quadratically (P ≤ 0.01) to day. Protein (%), total butterfat, and total Se, and somatic cells (cells/mL and cells/d) decreased linearly (P < 0.01) with day. Results indicate that gestational nutrition affects colostrum and milk yield and nutrient content, even when lactational nutrient requirements are met.

Factors affecting the reproductive performance of Awassi sheep flocks in north-east of Jordan: An epidemiological study

A prospective cohort study was conducted using 32 randomly selected Awassi sheep flocks to identify factors hypothesized to be associated with the occurrence of pregnancy, twinning and fetal loss between August 2005 and May 2006 in the region of Al-Safawi (northeast of Jordan). Vitamins A and E and selenium concentrations were determined on 448 blood samples. Using the forward selection procedure of the logistic regression module, models with statistically significant risk factors (P < 0.05) were constructed for three outcomes; pregnancy, twinning and fetal loss. Serum vitamin A concentration levels were associated with pregnancy (OR = 2.26, 2.48), twinning (OR = 6.49, 17.74) and fetal loss (OR = 0.13, 0.19). Primiparous ewes were 48% less likely to become pregnant than fourth or higher parity ewes. The likelihood of twinning increased significantly in ewes up to the third parity. Ewes that were fed 700-900 g barley, 250-300 g wheat-bran per head per day and grazed on vegetables residues were 4.15 times more likely to have twins than ewes that were fed 600 g barley and 200 g wheat-bran per head per day. Fetal loss in first and second parity ewes was about 3 times more likely than that in third or higher-parity ewes. Ewes pregnant with twins were about 14 times more likely to have fetal loss than ewes carrying single fetus. Pregnant ewes of the stationary flocks were 37% less likely to have fetal loss than ewes of the semi-nomadic flocks. These results demonstrate that stationary Awassi sheep flocks had higher pregnancy and twinning rates and less pregnancy loss. Supplementation of vitamin A, providing sufficient quantity of dry feed and increasing ram: ewe ratio for primiparous ewes of semi-nomadic flocks is essential to improve Awassi sheep reproductive performance.

Genetic analysis of milk production and composition in crossbred ewes from different maternal genotypes

Milk production and milk composition were measured in 1056 crossbred ewes managed under pasture grazing in a lamb production system. Most ewes were milked on three occasions at ~3, 4 and 12 weeks of lactation. The ewes were the progeny of mainly Merino dams and 91 sires from several maternal crossing breeds including Border Leicester, East Friesian, Finnsheep and Coopworth. The ewes were born over 3 years and run at three sites where they were joined naturally to meat rams. Most of the ewes were first parity (autumn-joined at 7 months of age and spring-joined at 14–17 months of age), with the remainder second or third parity. The cohorts of ewes and sites were linked genetically by three common maternal sires. The 4-h oxytocin-induced milking procedure was used to estimate daily milk production and milk samples were analysed for composition (fat%, protein% and lactose%). Daily milk yield and milk composition traits were analysed using restricted maximum likelihood mixed models procedures. The sire breed of crossbred ewes was significant for milk yield (P &lt; 0.01), fat% (P &lt; 0.01) and lactose% (P &lt; 0.05). There was a significant (P &lt; 0.01) interaction of sire breed × days of lactation, mainly due to the relatively higher milk yield of the East Friesian and White Suffolk cross ewes compared with the other crosses, at the end of the lactation. The East Friesian cross ewes had lower milk fat% than the other cross ewes. Ewes suckling multiple lambs had 29% higher peak milk yield than those bearing and suckling single lambs (P &lt; 0.001). There was an increase in peak milk yield of the ewes from first to second parity, and third parity ewes had a greater decline to the end of lactation causing a significant interaction (P &lt; 0.001). The overall decline in milk yield from peak to late lactation was –21.2 ± 0.7 g/day. Separate analysis showed a significant increase in milk yield with ewe pre-joining weight (regression 6.1 ± 1.8 g/day.kg). The estimate of heritability for daily milk yield was 0.24 ± 0.04 at 90 days of lactation and 0.10 ± 0.02 at 21 days of lactation. The estimates of heritability for the milk composition traits were generally moderate. Estimates of genetic correlations between measurements early and late in the lactation for milk yield and most composition traits were high. The within ewe by stage variance component estimates of repeatability were moderate to high for milk yield, fat% and protein%, with lactose% being low.

Comparison of non-linear growth models to describe the growth curve in West African Dwarf sheep

The objectives of this study were to compare the goodness of fit of four non-linear growth models, i.e. Brody, Gompertz, Logistic and Von Bertalanffy, in West African Dwarf (WAD) sheep. A total of 5274 monthly weight records from birth up to 180 days of age from 889 lambs, collected during 2001 to 2004 in Betecoucou breeding farm in Benin were used. In the preliminary analysis, the General Linear Model Procedure of the Statistical Analysis Systems Institute was applied to the dataset to identify the significant effects of the sex of lamb (male and female), type of birth (single and twin), season of birth (rainy season and dry season), parity of dam (1, 2 and 3) and year of birth (2001, 2002, 2003 and 2004) on the observed birth weight and monthly weight up to 6 months of age. The models parameters (A, B and k), coefficient of determination (R2), mean square error (MSE) were calculated using language of technical computing package Matlab®, 2006. The mean values of A, B and k were substituted into each model to calculate the corresponding Akaike’s Information Criterion (AIC). Among the four growth functions, the Brody model has been selected for its accuracy of fit according to the higher R2, lower MSE and AIC. Finally, the parameters A, B and k were adjusted in Matlab®, 2006 for the sex of lamb, year of birth, season of birth, birth type and the parity of ewe, providing a specific slope of the Brody growth curve. The results of this study suggest that Brody model can be useful for WAD sheep breeding in Betecoucou farm conditions through growth monitoring.

Parity effects on maternal behaviour are not related to circulating oestradiol concentrations in two breeds of sheep

Primiparous females of many species, including the sheep, do not show as competent maternal behaviour as multiparous mothers. In this study we investigated whether circulating concentrations of oestradiol might be related to this response, since breed differences in oestradiol concentrations have been shown to correlate with maternal behaviours. Oestradiol concentrations were measured in plasma collected at 2-weekly intervals from primiparous and multiparous ewes of two breeds (Scottish Blackface and Suffolk) throughout gestation, and maternal behaviour was recorded at parturition. Circulating oestradiol concentrations, and the ratio of oestradiol to progesterone concentration (O:P ratio) were higher in late pregnancy in Blackface ewes, but there were no significant effects of ewe parity. However, there was a significant interaction between breed and parity as O:P ratio was lower in primiparous Suffolk ewes compared to multiparous. This relationship was not seen in Blackface ewes. Blackface ewes of both parities groomed their lambs more frequently and made more low-pitched vocalisations than Suffolk ewes. Primiparous ewes were more likely to move as the lamb attempted to suck, and to show withdrawal or aggression towards the lamb. Primiparous Suffolk ewes also made more high pitched bleats than other classes of ewe. The data support previous studies which show an effect of breed on circulating oestradiol and O:P ratio but suggest that parity effects on maternal behaviour may be mediated by sensitivity to circulating concentration of oestradiol rather than variations in the plasma concentrations of this hormone.

Effects of parity and litter size on maternal behaviour in Kivircik ewes

Aim was to investigate effects of parity and litter size on grooming lambs, responses to sucking attempts of lambs, maternal behaviour score, and survival of their lambs in Kivircik ewes. Proportion of time spent grooming lambs was 0.34, 0.42, 0.41 and 0.45 in first, second, third and fourth parity ewes (P>0.05). Multiparous ewes stood and allowed lambs to suck for a greater proportion of sucking attempts compared with primiparous ewes. When the lamb attempted to suck, circling was the behaviour most often observed among ewe movement behaviours, whereas backing and moving forward behaviours were observed very rarely. Mean maternal behaviour score given to single and twin-lambed ewes were 2.87 and 3.36, respectively (P<0.05). The effect of ewe parity on survival of their lambs was not significant. However, mortality rate of twin lambs (19.2%) was significantly higher than that of single lambs (5.7%). Kivircik ewes did not increase the total maternal care to their lambs when they lambed twins, and time that the lamb received grooming attention in twin born lambs was about half of the time received grooming in single born lambs. Furthermore, survival rate of the twin born lambs was lower than that of single born ones.

Risk factors of lamb mortality in Pakistan

This study was carried out to investigate lamb mortality in 528 Pak-Karakul and 423 Thalli in Pakistan during 1998-1999. Mortality was 9 and 12% in the lambs of the two breeds, respectively. In Pak-Karakul lambs, pneumonia rendered the highest morbidity and mortality and all mortalities recorded were in the first week, whereas in Thalli lambs diarrhoea was at the peak, with 82 and 18% mortalities in the first and second week of life respectively. Birth weight of neonates that died was lower (P < 0.05) than that of the lambs that had survived. The correlation revealed a positive and significant (P = 0.000) relationship between birth weights of Pak-Karakul lambs and serum Ig, total proteins and globulin concentration. In Thalli lambs such a relationship was found in serum Ig and globulin concentration. Parity of ewes and sex of lambs in both breeds did not affect mortality rates. Lambs with Ig levels less than 20 zinc sulphate turbidity (ZST) units died while those with more than 20 ZST-units survived. Dams that lost their lambs had significantly (P < 0.05) lower values of colostral Ig than those with live neonates. Serum Ig concentration in survived neonates of both breeds had significant (P = 0.000) and positive correlation with colostral Ig of their dams. lamb mortality / Pak-Karakul and Thalli sheep / risk factors / Pakistan

Improving productivity of Malpura breed by crossbreeding with prolific Garole sheep in India

Garole, a prolific small sized sheep breed of India was introduced in the Mutton Project of the Institute during 1997 to explore the possibility of incorporating fecundity gene into Malpura (M) sheep of semi-arid region of Rajasthan. The data on reproduction and production traits of M and Garole × Malpura (GM) half-breds was used in the study to assess the improvement in evolved crossbred stock. The overall percent gain in prolificacy in GM was 52.38, which increased to 75.73 in third parity. The GM compared to M ewes also weaned more lambs per ewe lambed (1 versus 1.41). The lambing rate averaged 91.75 and 148.21% in M and GM ewes, respectively. The twin lambing percentage was only 4.71% in M flock while; it reached up to 51.10% in GM. Moreover, 5.72% of GM ewes produced triplets also. The genetic group non-significantly affect ewe efficiency (EE), but GM produced 3.3% more total lambs weight per ewe lambed at weaning and 6.15% more total lamb weight per ewe lambed at 6-month of age. The body weights at different ages of GM half-breds were lower ( P < 0.01) compared to contemporary M lambs. The parity of ewes significantly affects body weight from birth weight to 12-month of age. The survivability of GM half-breds was almost at par with the local M sheep. Results revealed that the fecundity genes responsible for increasing prolificacy have been incorporated into the GM and it might prove a valuable germplasm towards evolving a new prolific strain of sheep. The crossing of Garole with M increased the ewe efficiency.

Non-genetic factors affecting the reproduction performance, lamb growth and productivity indices of Djallonke sheep

Two important components that determine sheep production efficiency are reproduction and live bodyweight. An understanding of environmental factors affecting these traits is needed to implement optimal breeding and selection programs in Benin (West Africa). In this study, age at first lambing, length of the lambing interval, prolificacy, dam's post-partum weights, lambs weight at weaning and productivity indices of West African Dwarf sheep (Djallonke sheep) were analysed under research conditions. The non-genetic effects (season of birth, year of birth, parity of the ewes and sex of lambs) were determined. Age at first lambing (622.4 ± 55.6 days) was significantly ( p < 0.001) affected by year and season of birth. Lambing interval (242.6 ± 20.8 days) was affected ( p < 0.001) by the year of lambing, sex of the lamb, type of birth (single, twin), parity of the ewe and type of birth–parity interaction. The number of offspring per birth (1.4 ± 0.5) was significantly affected ( p < 0.001) by the year of lambing. Lamb weaning weights at 90 days of age (10.6 ± 2.1 kg) and ewe postpartum weights at lambing (27.5 ± 2.4 kg) were significantly affected ( p < 0.001) by all the fixed effects. Ewes with a heavier body weight exhibited shorter lambing intervals ( p < 0.001) and heavier offspring at 90 day of age ( p < 0.01). Productivity expressed as the body weight of a 90 days of old lamb produced per breeding female per year (17.0 ± 3.1 kg), per kg breeding female per year (0.6 ± 0.1 kg) and per kg breeding female per year (1.4 ± 0.2 kg) were affected ( p < 0.01) by the year of lambing, the parity of ewes, the sex of lambs, and the parity sex interaction. The number of births per month (95.7 ± 74.4) was higher during the rainy season than in dry season. Environmental effects estimated in this study are important and will need to be taken into consideration for sheep breeding improvement.

Breed, litter and parity effects on placental weight and placentome number, and consequences for the neonatal behaviour of the lamb

Lamb survival is impaired in low birth weight lambs, and those that are slow to stand and suck. Many of the factors that influence lamb vigour, such as parity, litter size, and breed, may exert their effects, at least partially, before birth by influencing placenta development. Our hypothesis was that retarded lamb behavioural development was due to differences in placentation in these animals. Data were collected from Blackface and Suffolk lambs in the first 2 h after birth and placentas were collected when delivered. Suffolk lambs, which were behaviourally slower and had lower rectal temperatures than Blackface lambs, were associated with larger but less efficient placentas (placental efficiency defined as foetal weight supported per g placenta) with fewer foetal cotyledons than Blackface placentas. Triplet lambs were significantly slower than twin or single lambs to suck and had lower rectal temperatures. Although placenta efficiency increased with litter size, placenta and cotyledon weight, and cotyledon number increased with twinning but not thereafter. It seemed likely that triplet lambs suffered some placental insufficiency in comparison to other litter sizes. Lambs born to first parity mothers were slower to stand and reach the udder than lambs of more experienced ewes, and first parity ewes also had smaller and less efficient placentas although cotyledon number was not affected. Male lambs tended to be slower than female lambs for most behaviours, although rectal temperatures were not affected. The sire of the lamb also influenced lamb behaviour and rectal temperature. Both lamb sex and lamb sire influenced the average weight of placental cotyledons, thus some of the sire effect on the behaviour and birth weight of his progeny might be mediated through placental development. Lamb neonatal vigour was correlated with placental efficiency suggesting that lamb behaviour immediately after birth is related to placental development and function.

Milk production capacity of priangan prolific sheep: II. The lactation curve

A calculation was made for the lactation curve of Priangan sheep using Wood equation to find out how much differences actual milk production of uncorrected ewes compared to those corrected using parity and litter size born. Milk production was measured using weighing of the lambs before and shortly after suckling, with average of daily and total milk production were 519.5 g/head and 43.6 kg head-1 lactation-1, respectively. The average of parameter a, which reflected milk production at the beginning of the lactation period was 6.296 that equivalent to 571.5 g/head and significantly affected (P<0.05) by parity. The b parameter which reflected the rate of milk increment at the beginning of the lactation period was found to be 0.528 and significantly affected (P<0.05) by parity. The c parameter which reflected the rate of milk decline at the end of lactation period was found to be -0.20 and significantly affected (P<0.05) by parity. The average persistency which reflected the duration of maximum milk production was found to be 22.58 days without any significant contribution of parity and the number of lamb born. The average time to reach maximum milk production was found to be at week 3.5 after lambing without any significant contribution of parity and litter size. The average estimation of maximum milk production was 708.4 g/head and significantly affected (P<0.05) by ewe parity. Key words : Milk production, lactation curve, Priangan sheep

Breed and parity differences in ovine placentation: Implications for placental efficiency and lamb vigour

Lamb vigour at birth (i.e. time to stand after delivery) is known to be affected by a number of maternal factors, such as parity and litter size (Dwyer, 2002), as well as lamb breed (Dwyer et al., 1996), and is related to subsequent lamb survival (Dwyer et al., 2001). It is likely that these factors act before birth to influence lamb development and may exert their effects through differences in placental development and function. The purpose of this experiment was to examine the effects of ewe parity, litter size and ewe breed on placental components, and relate these to lamb behavioural development at birth.