Heat stress is one of the most stressful events in livestock life, negatively impacting animal health, productivity, and product quality. Moreover, the negative impact of heat stress on animal product quality has recently attracted increasing public awareness and concern. The purpose of this review is to discuss the effects of heat stress on the quality and the physicochemical component of meat in ruminants, pigs, rabbits, and poultry. Based on PRISMA guidelines, research articles were identified, screened, and summarized based on inclusion criteria for heat stress on meat safety and quality. Data were obtained from the Web of Science. Many studies reported the increased incidences of heat stress on animal welfare and meat quality. Although heat stress impacts can be variable depending on the severity and duration, the exposure of animals to heat stress (HS) can affect meat quality. Recent studies have shown that HS not only causes physiological and metabolic disturbances in living animals but also alters the rate and extent of glycolysis in postmortem muscles, resulting in changes in pH values that affect carcasses and meat. It has been shown to have a plausible effect on quality and antioxidant activity. Acute heat stress just before slaughter stimulates muscle glycogenolysis and can result in pale, tender, and exudative (PSE) meat characterized by low water-holding capacity (WHC). The enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) act by scavenging both intracellular and extracellular superoxide radicals and preventing the lipid peroxidation of the plasma membrane. Therefore, understanding and controlling environmental conditions is crucial to successful animal production and product safety. The objective of this review was to investigate the effects of HS on meat quality and antioxidant status.

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.

In Tunisia, the recognition of the possibility of including longevity and disease resistance in dairy cattle selection objectives has been hypothesized as a useful strategy by both researchers and producers. However, in this paper, the state of the art, with a focus on health and longevity, is reviewed. Along the same lines, the heritability for the milk traits, fertility traits, and longevity of Tunisian Holstein dairy cows complies with the literature. Therefore, the influence of genetics on some diseases of the dairy cow was investigated. In addition, a decreasing efficiency in cow fertility has been observed over the last few years. The results showed that the risk of culling increased with common diseases. When analyzed with the Weibull model, functional lifespan was strongly influenced by milk yield; therefore, the risk increased with a reduced milk yield. In her first three lactations, the relative risk of selection increased gradually with lactation. Thus, the risk of thinning is highest at the beginning and end of the first feeding and the end of her second feeding. In conclusion, the risk of culling was reduced in parity. The factors that influence the life of the herd, such as health, husbandry, environmental conditions, and management, are often ignored when evaluating longevity.

Feed additives are crucial in livestock production, enhancing performance, health, and reproductive efficiency. Recently, there has been a shift toward natural biomolecules as feed additives, specifically targeting improved reproductive outcomes and sperm quality. This transition arises from concerns about antibiotic misuse, antimicrobial resistance, and consumer preferences for eco-friendly products, along with the superior bioavailability, lower toxicity, and reduced environmental impact of natural biomolecules compared to synthetic alternatives. Collaboration among researchers, veterinarians, nutritionists, and regulators is essential to ensure safe and effective livestock management. The review explores advancements in using vital biomolecules in reproductive processes, including plant-derived bioactives such as phytochemicals and antioxidants. It investigates not only the mechanisms but also the intricate interactions of these compounds with animals’ hormonal and physiological systems. Additionally, the review critically assesses challenges and prospects related to incorporating natural biomolecules into livestock practices. The potential benefits include enhanced reproductive efficiency and improved sperm quality. However, successful implementation requires understanding factors like precise dosing, potential interactions, and long-term health impacts. Overall, this comprehensive review highlights recent research, technological strides, and the future potential of integrating natural biomolecules into animal diets.

Background and Aim: Artificial insemination (AI) is a critical technique in sheep breeding programs, yet its success is influenced by factors such as semen quality, storage conditions, and insemination timing. This study examines the effects of different semen extenders, storage durations, and insemination schedules on semen motility and pregnancy rates in Palestinian Assaf sheep. The primary aim of this study was to assess and compare the efficacy of three semen extenders – Andromed, Indonesian, and Syrian – on the quality of stored semen and its subsequent effect on pregnancy rates following AI. In addition, the study investigated the impact of semen storage duration and the timing of insemination post-equine chorionic gonadotropin (eCG) injection on reproductive outcomes. Materials and Methods: Semen was collected from eight Assaf rams, diluted with one of three extenders, and stored at 4°C for up to 72 h. Sperm motility was analyzed using a computer-assisted sperm analysis system at different time intervals. AI was performed on 180 Assaf ewes across three farms in Palestine, with insemination conducted at either 48 h, 52 h, or both 48 and 52 h post-eCG injection. Pregnancy rates were determined through ultrasound 45 days post-insemination. Statistical analysis was conducted using the Statistical Package for the Social Sciences 22 (IBM® NY, USA), with p-values set at <0.05 for significance. Results: Semen motility decreased significantly over time, with total motility (TM) declining from 0.85 ± 0.01 (fresh) to 0.63 ± 0.02 after 3 days of storage. The Syrian extender exhibited superior fast motility (FM) (0.35 ± 0.01) compared to the others. Strong positive correlations were observed between TM and progressive motility (0.90, p ≤ 0.01). Pregnancy rates did not significantly differ among extenders (Andromed: 0.58 ± 0.06, Indonesian: 0.54 ± 0.07, Syrian: 0.56 ± 0.08). However, insemination performed at both 48 and 52 h post-eCG injection resulted in the highest pregnancy rate (0.62 ± 0.07), while the second ejaculation showed a tendency for improved fertility outcomes (0.61 ± 0.07). Conclusion: Prolonged semen storage negatively impacts motility, though the Syrian extender preserves FM better than the others. Pregnancy rates were not significantly influenced by the extender type but were optimized by insemination at both 48 and 52 h post-eCG injection. These findings highlight the importance of refining semen preservation techniques and timing AI procedures to enhance breeding success in Assaf sheep. Keywords: artificial insemination, breeding efficiency, Palestinian Assaf sheep, semen preservation.

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