Ethiopian Journal of Animal Production

Review on status of selection for heat tolerance improvement in Cattle

Tassew Mohammed — 2023-10-30

The objective is to review the status of selection for heat tolerance improvement in cattle. Economic losses due to heat stress have been significant. Heat stress occurs when THI greater than the animal’s thermo-neutral zone. Many strategies were suggested and implemented to mitigate heat stress. Among them, breeding for improved heat tolerance could be taken as a cost effective and long term solution of the problem. Animal breeding have showed rapid and appreciable advancement. Nowadays, quantitative based breeding has been complemented with molecular based breeding. Identification of heat tolerant cows could help to improve dairy performance through genetic selection. Several measures have been proposed as criteria to identify heat tolerant animals. Differences in thermal tolerance exist among cattle provide clues to select thermo-tolerant animals using genetic tools. The heritability of rectal temperatures under heat stress conditions in cattle ranged from 0.13 to 0.17. There is also heat shock gene related to thermo-tolerance that was identified and being used as marker in marker assisted selection and genome-wide selection to develop thermo-tolerant breeding bull. Heat tolerance genomic breeding values were developed for Holstein and Jersey bulls with reliability of heat tolerance of 30%. Breeding strategies to improve heat tolerance depend on the production system. The genetic mechanisms of heat-stress sensitive and tolerance should be identified before trying to improve heat resistance in dairy cows and in order to optimize the animal breeding program, it is important to add molecular genetic techniques along with the conventional animal breeding methods.

Estimation of non-genetic factors affecting birth weight and reproductive traits of pure Jersey dairy cattle at Adea Berga research station, Oromia, Ethiopia

Mekuryaw Wubie — 2024-03-05

This study was conducted to estimate the effect of non-genetic factors on birth weight and reproductive traits of pure Jersey dairy cattle at Adea Berga Research Station. A total of 9,207 pure Jersey dairy cattle performance records collected during 1986 to 2019 were used for the study. General Linear Model (GLM) procedures of SAS software were used to determine the effects of fixed factors. The results indicated that the overall least squares means (± SE) of age at first calving (AFC), calving interval (CI), number of service per conception (NSC) and birth weight (BW) were 32.68 ± 0.1 9 months, 479.80 ± 4.45 day, 2.01 ± 0.02 and 22.3 ± 0.0 9 kg, respectively. The results obtained for CI and NSC performance of pure Jersey dairy cattle at Adea Berga farm were high indicating the need of better management and selection. Year of birth had significant (p < 0.001) effect on AFC and BW. Similarly, the season of birth had significant (P < 0.001) effect on AFC. Postpartum cow weight (PPW) and parity of dam had also significantly (p < 0.05) influenced calf BW and CI. Furthermore, calving interval was significantly (p < 0.001) affected by year of calving. Therefore, improving the level of farm management system is essential for optimal reproduction performance of pure Jersey breed in the farm.

Meat quality of Sasso chicken fed rations from locally available ingredients at Nekemte, Ethiopia

Yosef Tariku — 2024-03-05

An experiment was conducted to evaluate meat quality of Sasso chickens fed rations from locally available ingredients in Nekemte city, Ethiopia. Four separate dietary treatments were used for the grower and finisher rations with varying the proportions of experimental diets used. A total of 120 male Sasso T44 chickens with 42 day-old were randomly assigned to treatment diets prepared separately for grower phase (8 weeks of age) and finisher phase (12 weeks of age) in a completely randomized design. The dietary treatments for the grower and finisher phases were formulated from the same feed sources (Table 1) but different in proportion of ingredients to satisfy both ME and CP requirements of the chickens. The four dietary treatments were: T1 [ maize + soybean + lupine + nougseed cake + limestone + salt coded as MSL]; T2 [Wheat grain + soybean + lupine + nougseed cake + limestone, salt + premix coded as WSL]; T3 [maize , wheat +soybean + lupine + nougseed cake + limestone + salt + premix coded as MWS] and T4 [Commercial ration, positive control coed as CR]. Before formulating the treatment diets, composition were done for percentages dry matter (DM%), crude protein (CP%), Crude Fiber (CF%), ether extracts fat (EE%) and total ash (ash%) from ingredients: maize, wheat, roasted? soybean, nougseed cake and roasted? lupin and were also mashed in to 3-5 mm sieve size to be palatable for the chickens. The treatments were replicated three times with 30 chickens per treatment. The General Linear Model (GLM) Procedures of the Statistical Analysis System (SAS, 2008) were used to analyze the data. Fifty consumer panelists involved in testing the sensory property of the meat. The sensory preference data were analyzed using the mixed model of the Statistical Analysis System (SAS, 2008) with the treatments taken as fixed effects and the sense of panelists as random effects. No significant (p > 0.05) difference was observed among chickens fed on the different experimental rations in most of the sensory meat quality parameters evaluated. Similarly, there was no significant (p˃0.05) difference in chemical composition of meat among Sasso chickens fed on the different dietary treatments, except for pH. The pH of Meat from
chickens fed on MSL and WSL were significantly lower than those fed on MWS and CR. However, meat quality of Sasso chickens fed on both CR and MWS was almost similar, based on their pH values, but lower than those which fed WSL. From this it can be concluded that WSL can be used as an alternative feed source to CR in broilers’ ration without any adverse effects on meat quality of Sasso chickens in the study area and areas with similar agro-ecologies of the country.

Chemical composition and ruminal fermentation characteristics of selected forage species from traditional enclosure areas in the central highlands of Ethiopia

Teklu Wegi — 2024-03-05

This study aimed to characterize key forage species in terms of their chemical composition and ruminal fermentation characteristics thereby determining their nutritional value for ruminants. A total of 20 plots of 40 m x 40 m were established on pasture land in the highland and mid-highland agro-ecologies. Sixteen quadrats (0.5 m x 0.5 m) were randomly laid per plot and samples of 19 key forage species were collected at 50% flowering stages. Species identification was done on site by using guide books and a trained technician. The harvested pasture was sorted by species to allow the investigation between species variability in terms of nutrient contents and in vitro ruminal fermentation parameters. Forage species evaluated in the current study showed noticeable variation in nutritive values and ruminal fermentation parameters. Principal component (PC) analysis showed that the first three PC (PC1, PC2 and PC3) explained 84.2% of the total variation in the dataset. The key forage species clustered according to their chemical composition and in vitro fermentable parameters into five main groups. Centella asiatica forb (sole group) was superior in gas production at 24 h, fractional gas production rate (c) and effective gas production (EGP) but lower in neutral detergent fiber (NDF) and CH4 production. Forage legumes
were clustered close to each other and had higher crude protein (CP), ‘c’, and EGP production compared to forage grass. Forage grasses except Eragrostis tenuifolia were characterized by higher CH4 production compared to others. Therefore, appropriate management practices that maintain balanced proportions of herbs, forage legumes, and grasses may result in improved ruminal fermentation of the available diet while reducing methane emissions by ruminants fed on native pasture.

Productive and reproductive performances of Tikur sheep in Gubalafto district of North Wollo Zone, Ethiopia

Tassew Mohammed — 2023-10-30

The study aimed to evaluate the productive and reproductive performance of Tikur sheep. Two villages were purposely selected, whereas 62 households were randomly selected to use their sheep in the monitoring study. A total of 1015 sheep with varied ages were involved. Productive traits were measured using a spring balance scale (50 kg capacity with 100g precision), while reproductive data will be collected by recording animals that gave birth during the monitoring period by trained enumerators. Both productive and reproductive data were analyzed using SAS (9.40). The overall means of birth, weaning, six-month, nine-month, and yearling weights of
the sheep were 2.47±0.47, 11.89±2.26, 15.76±1.49, and 16.49±1.25 and 21.33±3.27 kg, respectively, whereas the means of age at first mating, age at first lambing, and lambing interval were 8.36±0.92, 13.94±0.86, and 8.92±1.10 months, respectively. The annual reproductive rate and litter size were 1.44±0.26 lambs per ewe per year and 1.04 lambs per lambing, respectively. Seasons and years of birth, types of birth, and parity of birth significantly affected most of the productive and reproductive traits. The overall lamb mortality was 9.04%, whereas the major causes of mortality included pasteurellosis, parasites, and circling diseases. The study indicates that the performances of Tikur sheep are found to be good for major productive and reproductive traits. The results of the study can serve as baseline information to take necessary actions for sheep genetic improvement and conservation. The sheep flock management should consider significant non-genetic factors.