Muayad Salman

Background: Assaf sheep are a major source of meat and milk in the northern West Bank, Palestine, yet limited information exists regarding their phenotypic and morphometric characteristics under local management conditions. Understanding these traits is essential for improving productivity, reproductive performance, and breeding strategies. Aim: This study aimed to investigate the morphology, productive traits, and reproductive performance of Assaf sheep raised in four governorates of the northern West Bank. Methods: A total of 580 adult sheep (520 ewes and 60 rams) were evaluated for both qualitative and quantitative traits across Jenin, Tulkarm, Nablus, and Jericho. Morphometric measurements, live weights, milk yield, prolificacy, lamb birth weight, and udder dimensions were recorded. Multivariate analysis was used to assess variability within the population and identify traits associated with productivity improvement. Results: Pronounced sexual dimorphism was observed, with males exhibiting higher average live weights (113.0 kg) and body lengths (116.9 cm) than females (72.7 kg and 85.5 cm, respectively). Productive traits varied by region and management practices, with the highest milk yield in Tulkarm (407 ± 19 kg/lactation) and the lowest in Jericho (255 ± 17 kg/lactation). Prolificacy increased with parity, averaging 1.15 lambs in the first parity and 1.61 lambs in the third. Lamb birth weights reflected regional differences, with Tulkarm lambs reaching the highest average (4.69 ± 0.07 kg), and singletons (4.72 kg) were heavier than multiples (4.30 kg). Morphometric traits associated with productivity were evident in udder measurements, with average udder length and depth of 21.4 and 15.1 cm, respectively. Conclusion: The study highlights significant variability in Assaf sheep phenotypic and productive traits across regions. These findings provide essential information for breeding programs and management strategies aimed at improving sheep productivity and reproductive performance in the northern West Bank.

This study was conducted to explore the associations between morphometric, reproductive, and growth traits of Palestinian Assaf sheep raised in the northern West Bank, Palestine. Data were collected from January to May 2025, with a total of 520 ewes sampled from 26 flocks. Studied traits (not limited to) were pelvic width (PW), chest depth (CD), body condition score (BCS), number of lambs born per birth (NLB), prolificacy (PRO), weight at first lambing (WAL), lamb birth weight (LBW), and weaning weight (WWT). Results from statistical analysis revealed strong correlations (r= 0.79; p0.3) with reproductive performance traits. Additionally, WWT was linked to both BCS and ADM (r= 0.45; p<0.01). It was concluded that introducing morphometric traits, mainly those indicated as body capacity and pelvic structure in breeding programs for Assaf sheep, can improve not only the performance of reproduction and milk production, but also on-farm production levels, adaptability, and multi-trait merit.

As global demand for sheep products increases, improving reproductive efficiency and lamb growth performance has become a priority for sheep farmers. Artificial insemination (AI) offers several advantages over natural mating, including improved genetic selection and disease control. This study contributes to understanding the impact of different mating methods and semen preservation techniques on reproductive performance and growth traits in Palestinian Assaf sheep under local breeding conditions. The research included 123 adult Assaf ewes from two farms, which were hormonally synchronized and divided into three groups for different reproductive biotechnologies. Group 1 (G1) comprised 50 ewes inseminated with frozen semen straws, while Group 2 (G2) had 37 ewes inseminated with fresh semen from genetically superior rams. Both G1 and G2 used 0.5 mL straws containing 250 million sperm, with insemination occurring 48 h post sponge removal and eCG hormone injection. Group 3 (G3) consisted of 36 ewes that underwent natural mating at a ratio of 1 ram to 6 ewes. The study revealed that insemination methods significantly affected fertility rates (45.4, 61.1, and 71.9% for G1, G2, and G3, respectively; p < 0.05). Artificial insemination notably enhanced lamb performance indicators (p < 0.05), although it did not significantly influence prolific lambing (p > 0.05). Prolific lambing significantly impacted birth weight, weaning weight, and average daily gain at 60 days across all groups (p < 0.05), but not the average daily gain or final weight at 180 days (p > 0.05). The management system significantly affected birth and weaning weights at 60 days (p < 0.05), but not the final weight at 180 days or prolific lambing (p > 0.05). Lamb sex significantly influenced average daily gains at 60 and 180 days, as well as final weight at 180 days (p < 0.05). The findings suggest that, while artificial insemination with semen from elite rams may reduce fertility rates, it significantly improves lamb performance rates. In conclusion, our study demonstrates that, while natural mating offers higher fertility rates, AI with fresh semen can be a valuable tool for improving lamb growth performance in Palestinian Assaf sheep. These findings provide valuable insights for sheep farmers in the region to optimize reproductive strategies and enhance lamb production

Data on 1440 Awassi (AW), 2114 Assaf (AF), 261 Crossbred (XB), and 439 Improved Awassi (IA) lamb genotypes from 689 AW, 1009 AF, 105 XB, and 195 IA dams, and 152 sires, obtained from three geographical districts in the West Bank and collected between 2010 and 2015, were analyzed to estimate (co)variance components and genetic parameters for pre-weaning growth traits, including birth weight (BW), weaning weight (WW), pre-weaning average daily gain (PADG), and Kleiber ratio (KR). Explanatory statistical analyses employed the least squares method of the following factors: lamb genotype, mating type (natural mating or artificial insemination), lamb sex, and birth type, on lamb pre-weaning growth traits. The estimation of genetic parameters was performed by an animal model in Restricted Maximum Likelihood (REML) The heritability estimates for lamb traits showed that AF lambs had the highest heritability for KR 0.62, while IA lambs had a relatively high heritability for PADG 0.42. In terms of genetic correlations, the correlation between birth weight and PADG was strongest in AW 0.80, and IA lambs had a negative genetic correlation between BW and WW −0.28. For maternal genetic correlations, AF lambs exhibited a high maternal correlation between BW and WW 0.78, and AW lambs had a strong maternal correlation between PADG and KR 0.57. Phenotypic correlations were particularly strong in XB lambs between BW and KR 0.79. It was concluded that IA lambs had higher BW, and AF lambs excelled in WW and PADG. These results indicated the potential for genetic improvement in feed efficiency among AF lambs, whereas AW lambs exhibited a stronger environmental influence on growth traits.