Dereje Tadesse

Heat stress is a major challenge to livestock production; affecting physiological homeostasis, metabolic function, and productivity. Although goats possess adaptive mechanisms to cope with elevated temperatures, prolonged heat exposure can compromise their health and performance. Antioxidant supplementation has been proposed as a nutritional strategy to mitigate the negative effects of heat stress; however, information on the efficacy of plant-derived antioxidants such as Artemisia absinthium remains limited. Therefore, this study evaluated the effects of ascorbic acid (ASC; vitamin C), Artemisia absinthium (ART; wormwood), and their combination on thermoregulatory, hematobiochemical, and gene expression responses in heat-stressed Spanish goats. Thirty-two adult female goats (4–5 years old; 48.8 ± 8.1 kg) were stratified by body weight and randomly assigned to four treatments (n = 8 per treatment): control (CON; no supplement), ASC (2 g/goat/day), ART (2 g/goat/day), and ASC+ART (1 g each/goat/day), and supplemented for 42 days under summer grazing conditions. Ambient temperature and relative humidity were recorded hourly to calculate the temperature–humidity index (THI). Rectal temperature (RT), respiratory rate (RR), and coat surface temperature (CST) were measured weekly. Blood samples were analyzed for packed cell volume, albumin, total protein, blood urea nitrogen, cholesterol, triglycerides, creatinine, thyroxine, and glucose. Peripheral blood mononuclear cells were isolated for gene expression analysis of HSP70, CAT, and GPX1 by quantitative PCR. Heat production was measured in a subset of goats using respiratory calorimetry. Physiological and blood data were analyzed using the MIXED procedure of SAS, whereas gene expression data were analyzed using one-way ANOVA. Mean THI, ambient temperature, and relative humidity during the study were 78.0 ± 0.44, 28.7 ± 0.69 °C, and 62.9 ± 1.08%, respectively, confirming sustained heat stress conditions. Rectal temperature was significantly higher in the ASC+ART group than in the other treatments (p < 0.05). Respiratory rate also differed among treatments (p < 0.01), with higher values in the ART and ASC+ART groups. The coefficient of heat tolerance was significantly affected by treatment (P = 0.033), and the ASC+ART group had the lowest value. Heat production per unit metabolic body weight was significantly lower in the ART group than in the other groups (p < 0.05). Triglyceride concentrations were significantly lower, whereas glucose concentration was significantly higher, in the ART group (p < 0.05). Expression of GPX1, CAT and HSP70 was significantly lower in supplemented groups than in the control group, indicating reduced oxidative stress. In conclusion, individual supplementation with Artemisia absinthium improved metabolic efficiency and favorably altered selected biochemical and molecular responses under heat stress, whereas ascorbic acid had limited effects. The combined treatment did not improve thermoregulation and appeared less favorable than Artemisia absinthium alone.

The study was conducted to determine appropriate numbers and times of daily gas measurements to estimate total daily methane (CH₄) emission of meat goats using a GreenFeed system (GFS). A replicated 4 (four measurement protocols) × 4 (four periods) Latin square design was employed with 16 Boer wethers in a confinement pen setting. Measurement protocols entailed three (G-3T; 0600–0700, 1400–1500, and 2200–2300 h), four (G-4T; 0700–0800, 1300–1400, 1900–2000, and 0100–0200 h), and six (G-6T; 0800–0900, 1200–1300, 1600–1700, 2000–2100, 0000–0100, and 0400–0500 h) times for daily measurement periods in GFS. The fourth protocol was continuous measurement over 24 h with animals in an open-circuit respiration calorimetry system (CS). Oat hay was given in individual feeders, and a small predetermined quantity of a pelleted concentrate supplement (bait) was dispensed by the GFS or manually offered for the CS. Overall, total dry matter (DM) intake (614, 625, 635, and 577 g/day for CS, G-3T, G-4T, and G-6T, respectively; SEM = 13.9) and digestible DM intake (359, 368, 374, and 320 CS, G-3T, G-4T, and G-6T, respectively; SEM = 15.9) were lower for CS than for G-3T, G-4T, and G-6T (p < 0.05), but these variables were not different among the GFS protocols. There was a significant (p < 0.001) effect of measurement protocol on CH₄ emission in g/day (11.1, 25.6, 27.3, and 26.7 for CS, G-3T, G-4T, and G-6T, respectively; SEM = 1.11), g/kg DM intake (19.3, 46.4, 43.9, and 42.4 for CS, G-3T, G-4T, and G-6T, respectively; SEM = 2.03), and g/kg body weight (0.49, 1.11, 1.18, and 1.16 for CS, G-3T, G-4T, and G-6T, respectively; SEM = 0.052), with values being much lower for CS than for G-3T, G-4T and G-6T. Conversely, CH₄ emission was similar among the GFS protocols despite differences in the time and number of daily visits (2.03, 2.76, and 3.75 visits for G-3T, G-4T, and G-6T, respectively; SEM = 0.114; p < 0.001). Pearson correlation (r) analysis indicated a moderate to high (p < 0.05) correlation between CS and G-3T (r = 0.62 for CH₄ in g/day and r = 0.59 for CH₄ in g/kg BW), CS and G-4T (r = 0.67 for CH₄ in g/day and r = 0.76 for CH₄ in g/kg BW), and CS and G-6T (r = 0.70 for CH₄ in g/day and r = 0.75 for CH₄ in g/kg BW). However, the correlation coefficient for CH₄ in g/kg DM intake was low between CS and G-3T (r = 0.11) and CS and G-6T (r = 0.31) but slightly greater between CS and G-4T (r = 0.47). In conclusion, the results suggest that CH₄ emissions using GFS in a confinement setting were greater compared with the CS in goats, but CH₄-emission estimation using the GFS correlated with the CH₄ emission in the CS system with a stronger relationship for the four times of daily measurements.

Physiological and blood measurement changes due to high heat load, restricted feed intake, and limited drinking water availability in 135 animals of three hair sheep breeds (Dorper, Katahdin, and St. Croix) were subjected to multivariate analysis techniques. The objective of this analysis was to evaluate the ability of these variables to separate individual hair sheep into groups based on adaptation characteristics in response to three physiological stressors and identify variables with greater discriminatory power. There were 16, 8, and 13 physiological and blood variables obtained from high heat load, restricted feed consumption, and water intake studies, respectively, for multivariate analysis. Physiological variables such as respiration rate, rectal and skin temperature, and panting score were measured only in the heat stress study. The results of the cluster and canonical discriminant analyses showed the presence of wide divergence (p < 0.05) between St. Croix and other breeds in their responses to high heat loads and restricted-feed- and -water-intake conditions. Dorper and Katahdin were grouped (p > 0.05) together based on the changes in physiological variables, which were separated (p < 0.05) from those of St. Croix as a resilient group. The stepwise discriminant analysis indicated that skin temperature, panting score, rectal temperature, respiration rate, and blood urea nitrogen and oxygen concentrations were the significant (p < 0.05) discriminating variables in clustering individual sheep into groups based on their responses to the high-heat-stress condition. Under the limited feed intake condition, the significant (p < 0.05) traits responsible for the separation of St. Croix from Dorper and Katahdin were blood triglyceride and cholesterol concentrations, whereas blood hemoglobin, osmolality, protein, and albumin were most important discriminating variables under the limited water intake condition. In conclusion, the results of the present study suggest that the stress responses of Dorper and Katahdin are similar and different from that of St. Croix. This finding can be useful information for future decisions in developing climate-resilient sheep through selective breeding.

Forty-six Dorper (DOR), 46 Katahdin (KAT), and 43 St. Croix (STC) female sheep (initial body weight of 58, 59, and 46 kg, respectively, SEM = 1.75; 3.3 ± 0.18 years of age, 2.6–3.7), derived from 45 commercial farms in four regions of the USA (Midwest, Northwest, Southeast, and central Texas), were used to evaluate responses in blood constituent concentrations to increasing heat load index (HLI) conditions. There were four sequential 2 weeks periods with target HLI during day/nighttime of 70/70 (thermoneutral zone conditions), 85/70, 90/77, and 95/81 in period 1, 2, 3 and 4, respectively. A 50% concentrate pelletized diet was fed at 53.3 g dry matter/kg body weight^0.75. The analysis of most constituents was for samples collected on the last day of the second week of each period at 13:00 h; samples for cortisol, thyroxine, and heat shock protein were collected in week 2 and 8. Previously, it was noted that resilience to high HLI conditions was greatest for STC, lowest for DOR, and intermediate for KAT. There were few effects of region. Other than hemoglobin concentration, there were no interactions between breed and period. Blood oxygen concentration was greatest (p < 0.05) among breeds for STC (5.07, 5.20, and 5.53 mmol/L for DOR, KAT, and STC, respectively; SEM = 0.114) and differed among periods (4.92, 5.26, 5.36, and 5.52 mmol/L for period 1, 2, 3, and 4, respectively; SEM = 0.093). There were breed differences (i.e., main effects; p < 0.05) in glucose (50.0, 52.6, and 52.1 mg/dL; SEM = 0.76), urea nitrogen (17.2, 17.3, and 19.4 mg/dL; SEM = 0.33), creatinine (0.991, 0.862, and 0.802 mg/dL; SEM = 0.0151), total protein (6.50, 6.68, and 6.95 g/l; SEM = 0.017), triglycerides (28.4, 29.1, and 23.5 mg/dL; SEM = 0.87), and cortisol (6.30, 8.79, and 6.22 ng/mL for DOR, KAT, and STC, respectively; SEM = 0.596). Differences among periods (p < 0.05) were observed for lactate (27.9, 25.3, 27.8, and 24.0 mg/dL; SEM = 0.99), creatinine (0.839, 0.913, 0.871, and 0.917 mg/dL; SEM = 0.0128), total protein (6.94, 6.66, 6.60, and 6.65 g/l; SEM = 0.094), and cholesterol (60.2, 56.5, 58.3, and 57.6 mg/dL for period 1, 2, 3, and 4, respectively; SEM = 1.26). In addition, the concentration of cortisol (7.62 and 6.59 ng/mL; SEM = 0.404), thyroxine (5.83 and 5.00 µg/dL; SEM = 0.140), and heat shock protein (136 and 146 ng/mL for week 2 and 8, respectively; SEM = 4.0) differed between weeks (p < 0.05). In conclusion, the lack of interaction between breed and period with different HLI conditions suggests that levels of these blood constituents were not highly related to resilience to high HLI.

The study was carried out to evaluate the effect of genotypes and concentrate levels on growth performance and carcass characteristics of Bati, Hararghe highland (HH) and Short eared Somali (SS) goat types found in Ethiopia. A 3 × 2 factorial arrangement (3 genotype × 2 concentrate levels) was used to randomly allocate 36 goats (15.2 ± 0.30 kg initial weight); 12 goats from each genotype with age about 1 year were divided randomly into two groups for a feeding trial of 90 days. The two concentrate levels were L1 and L2, where L1 and L2 are levels fed to animals at the rate of 1 and 1.5 % BW, respectively. Hay was fed ad libitum with 20 % refusal rate. The mean daily dry matter intake of the goats was 520.5 g/day. The intake was about 67 g/day higher for L2 than L1 goats. Consequently, L2 goats had significantly (p < 0.05) higher average daily gain, dressing percentage, primal carcass cuts and total non-carcass fat than those fed L1. Among genotypes, HH goats were found to have higher (p < 0.05) carcass weight, heart girth, neck girth, and carcass cuts (legs and shoulders) than SS goats. However, they were not better in dressing percentage than SS goats. Compared to Bati goats, HH goats had significantly (p < 0.05) wider rib-eye area, heavier ribs/racks weights, and better dressing percentage. Despite smaller body size, the performance of SS goats was comparable to Bati goats. In conclusion, the study indicates the potential of Ethiopian indigenous goats to produce optimum amount of meat when supplemented with concentrate at the rate of 1.5 % body weight.

A 3 × 2 factorial experiment was carried out to evaluate the effect of breed or genotype and levels of concentrate on muscle composition and skin and leather quality characteristics. The three indigenous goat genotypes used were Bati, Hararghe highland (HH), and short-eared Somali (SS), (12/genotype) with an average initial weight of 15.2 ± 0.245 kg. The goats were all males ~1 year of age. After grouping based on their initial weight, they were randomly assigned to two levels of concentrate feeding (six goats per genotype per treatment) and fed for 90 days. The two concentrate feeding levels were C1 and C2, where goats were fed at 1% and 1.5% of their bodyweights, respectively. At the end of the study, all goats were slaughtered and samples were taken from the longissimus muscle for chemical composition analysis. The skins were weighed, preserved and processed into leather for physico-chemical analysis. The longissimus muscle of SS goats had higher (P < 0.05) fat content (7.01%) than Bati (6.05%) and HH (6.02%) goats. Feeding concentrate at 1.5% bodyweight increased carcass weights (P < 0.01), and increased the protein and fat contents of the longissimus muscle by ~5.4% and 3.5%, respectively. Similarly, goats under C2 feeding group had heavier skin than those under C1. However, Bati and HH goats produced 250 g more heavier leather than SS goats. Leathers made from skins of HH goats were thicker (1.56 mm) than those from Bati (1.32 mm) and SS goats (1.23 mm). Leathers from SS goats tended to have lower (P = 0.07) tear strength and higher (P = 0.05) fat content than those from Bati and HH goats. Goats fed C2 produced leathers with higher (P < 0.05) tear strength (51.6 N/mm) and fat content (6.2%) than those fed C1. In conclusion, the study revealed that the meat obtained from the three goat types had low to medium fat content that can meet the needs of diversified consumers. Moreover, they produced quality leather comparable to the quality standard set for good quality leather despite leathers from SS goats tending to have lower tear strength and higher fat content.

A study was carried out to understand the needs and perception of goat keepers in selected areas of Ethiopia in order to identify the breeding objectives, traits of preference, and production constraints that may be required in designing improvement programs. The study was conducted in three districts (Bati, Meta, and Kebri-Beyah) representing the lowland crop-livestock (LLCL), highland cereal-livestock (HLCL), and pastoral/agropastoral (P/AP) systems, respectively. The study targeted the three goat types (Bati, Hararghe Highland, and Short-eared Somali) found in Ethiopia. Households in all systems considered meat production, milk production, and income generation as major purpose of keeping goats. However, those in the low rainfall and arid environments of P/AP systems gave high ranking to adaptability to harsh environments and also to building social and religious values. In LLCL and HLCL systems, goat skin and manure were more valued than in P/AP systems. Principally, in P/AP systems, the awareness of households to skin utilization and marketing was very low. Despite diverse multiple breeding objectives identified, household breeding practices were affected by constraints related to disease prevalence, feed shortage and water scarcity, and lack of awareness on skin management, utilization, and marketing. Thus, designing and implementing of sustainable goat improvement programs is an overriding priority and should take into account the breeding objectives and knowledge of goat keepers in all production systems. Along with the breed improvement, a strategy should also be devised to enhance the utilization and marketing of goat skin at all levels of production.