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61.
The present study included 3,358 observations of 675 bulls and heifers from the Iowa State University beef cattle breeding project. Data were collected over a 3-yr period between 1998 and 2000. Each year, cattle were scanned four to six times for ultrasound-predicted percentage of intramuscular fat (UPFAT) and other ultrasound traits, starting at a minimum age of 28 wk. The objective of the current study was to estimate variance components, heritability, and repeatability of UPFAT in young bulls and heifers. Data were subjected to random-regression animal models that included fixed effects of contemporary group, fixed Legendre polynomial of age at measurement, and random regression coefficients on Legendre polynomial of age at measurement for animals' direct genetic and direct permanent environmental effects. Phenotypic and genetic models involving different levels of polynomial fit for the animal component were considered. A model fitting a linear effect of Legendre polynomial of age at a measurement for animal direct genetic and direct permanent environmental effects and a homogeneous error variance described the present data adequately. Heritability of UPFAT ranged from 0.32 at 28 wk of age to a maximum of 0.53 at 63 wk. Repeatability of UPFAT increased from a minimum of 0.60 at ages of 28 to 39 wk to a maximum of 0.80 at ages 61 to 63 wk. Heritability and repeatability of yearling UPFAT were 0.50 and 0.71, respectively. With the exception of minor differences at earlier ages, fitting heterogeneous error variances did not have an effect on genetic parameter estimates for most ages of measurement. The present results showed an optimal heritability and repeatability of UPFAT measures around 52 wk and through at least 63 wk of age. This suggested that differences in UPFAT measures during this period also are good measures of differences in marbling genetic potential of Angus cattle. 相似文献
62.
The objective of the study was to estimate variance components, heritability, and repeatability of ultrasound longissimus muscle area (ULMA) measures. Data included 4,653 serial ULMA measures from 882 purebred Angus bulls and heifers. Animals were born over a 4-yr period from 1998 to 2001. Each year, bulls and heifers were ultrasonically scanned four to eight times, with a 4- to 6-wk interval between scans. Initially, data were subdivided by scan session across years and were analyzed in a multitrait model (MTM). Data pooled across years and scan session were then analyzed using random regression models (RRM) to estimate trends in genetic parameter estimates. Additive direct genetic variance increased with advancing scan session ranging from 8.67 cm4 at the first scan (mean age = 35 wk) to a maximum of 19.48 cm4 at the sixth scan (mean age = 56 wk). Heritability of ULMA increased from 0.35 at first scan to a maximum of 0.48 at the fourth scan (mean age = 50 wk). Additive direct genetic variance and heritability values at about 1 yr of age (fifth scan) were 18.24 cm4 and 0.45, respectively. Estimates from RRM also showed an increase in sigma(a)2 and h2 with age. Trends in sigma(pe)2 estimates, although tending to fluctuate, also increased with age. Additive direct genetic variance at 1 yr of age ranged from 15.8 cm4 to 17.0 cm4 for the different models. Heritability of yearling ULMA measures ranged from 0.40 to 0.42 and repeatabilities ranged from 0.80 to 0.84. For the range of ages used in the current study, both MTM and RRM showed close to maximum heritability values at around 1 yr of age. Therefore, phenotypic differences in yearling ULMA between Angus cattle are better indicators of genetic differences than earlier measurements. Angus breeders could, therefore, use ULMA measures made at around 1 yr of age to select next generation parents. 相似文献
63.
Haile A. Hassen H. Gatew H. Getachew T. Lobo R. N. B. Rischkowsky B. 《Tropical animal health and production》2018,50(3):643-650
Tropical Animal Health and Production - We generated epidemiological information on the prevalence of nematode parasites and possible resistance/resilience of goats in three areas, Bati, Shinille,... 相似文献
64.
Hassen Chaka Gezahegn Aboset Abebe Garoma Balako Gumi Eric Thys 《Tropical animal health and production》2018,50(5):1041-1049
A cross-sectional survey was carried out to investigate the seroprevalence of ovine and bovine brucellosis in the livestock–wildlife interface area of Nechisar National Park, Ethiopia. Furthermore, producer’s knowledge about brucellosis and its zoonotic potential was assessed using a structured questionnaire. A total of 268 cattle and 246 goat sera were collected from 50 herds and 46 flocks and subjected to Rose Bengal test (RBT) and enzyme-linked immunosorbent assay (ELISA) in parallel to detect anti-Brucella species antibodies. Positive reactions were further confirmed with compliment fixation test (CFT). Flock and herd level seroprevalence rate was 12.8% (95% CI 4.8–25.7) and 32.0% (95% CI 19.5–46.7) in goats and cattle, respectively. An overall animal-level seroprevalence of 4.5% (95% CI 2.25–7.86) and 9.7% (95% CI 6.44–13.89) was recorded for goats and cattle, respectively. Seroprevalence showed an increasing trend with age, where adult cattle >?2 years. Goats (>?1 year) recorded relatively higher seroprevalence, but the differences were not statistically significant. Similarly, female cattle and goats recorded a relatively higher seroprevalence, 11 and 5.6%, respectively, compared to males but the difference was not significant. However, a significant (P <?0.01) variation of seroprevalence was noted for parity (bovine), higher in animals in second parity, and abortion history, in both species, higher in animals that experienced abortion. Interviews revealed lack of awareness about brucellosis and food safety related to the zoonotic potential from consuming raw animal products (milk and meat). Ninety-eight percent of respondents did not consider handling abortion material is risky, and only a very low proportion (8%, n?=?50) was able to mention limited zoonotic diseases (anthrax and Taenia cysticercosis) could be transmissible to people. The study indicated that brucellosis is endemic in domestic animals in the interface area and calls for further broad epidemiological investigation of the disease in livestock, human and wildlife following ‘one health’ unified research approaches beside enhancing public awareness. 相似文献
65.
Ashenafi Assefa Yisehak Kechero Taye Tolemariam Assefa Kebede Eshetu Shumi 《Tropical animal health and production》2018,50(4):727-732
Condensed tannins (CT) extracted from Balanites aegyptiaca, Tamarindus indica, and Celtis toka browses were used to evaluate their anthelmintic effect on different developmental stages of Haemonchus contortus. To achieve this objective, various serial concentrations of each CT extract of the foliages were used to test adult motility, inhibition of egg hatchability, and larval development. The fodders were selected based on their multipurpose advantage and accessibility to use as fodder for livestock in the low lands of the Gambella region. The fastest and slowest adult motility rate was observed in 2-ml (4 min) and 0.125-ml dose of C. toka, respectively, which is better than that in ivermectin. Egg hatchability inhibition was observed with dose difference within species, but there is no difference between B. aegyptiaca and T. indica. The foliage extracts of the studied browses were observed to inhibit the larvae by 100% at 2 ml, which is similar to ivermectin. There is no significant difference observed in larvae development inhibition between the species and ivermectin (p?>?0.05). CT extracts of studied plants have found to own significant anthelmintic activity in a dose-dependent manner. They could serve as anthelmintic economically and eco-friendly after further and series of in vivo experiments. 相似文献
66.
A total of 32 Horro (Bos indicus) bulls, with an average initial body weight and age of approximately 211 kg and 6 years were evaluated. The bulls were divided
into two treatment groups. One group was given a supplementary concentrate at a rate of 1.5 kg/day and the second group served
as the control and received no supplementation. The observation period lasted for 50 weeks. Semen was collected every two
weeks by mean of electrical stimulation with the aid of an electro-ejaculator. The percentage of abnormal sperm (total abnormalities,
head, midpiece and tail) remained lower in the supplemented group than in the non-supplemented group. The percentage of live
sperm tended to be higher in the supplemented group throughout the 50-week trial period. Until week 17 of the trial there
were no significant differences; however, starting at week 18 there were significant differences between the two treatment
groups except for week 26. Thereafter, significant differences were recorded until week 38; from week 40 no significant differences
were observed between the two groups in respect of percentage of live sperm (except for week 48). Season (week) during which
the semen samples were collected had no significant effect on the percentage of abnormal sperm in both treatment groups (supplemented
and non-supplemented). At the start of the trial the nutritionally supplemented group had a higher occurrence of sperm abnormalities
(11.4% ± 1.1%) compared to 8.3% ± 1.3% in the control group. Thereafter, sperm abnormalities declined rapidly in the supplemented
group (except for week 50). The sperm abnormalities for the non-supplemented group showed a tendency to increase during the
entire observation period. 相似文献
67.
A prototype system was developed and constructed for automating the measurement and recording of canopy-, soil-, and air temperature, and soil moisture status in cropped fields. The system consists of a microcontroller-based circuit with solid-state components for handling clock/calendar, sensor power, and data storage and retrieval functions. Sensors, including an analog soil moisture sensor, analog and digital temperature sensors, and a digital infrared thermometer, are widely available and inexpensive. The circuit board and sensor assemblies require approximately 4 h to construct and test, and material costs totaled approximately US$84. Systems were built and tested during the 2009 growing season in a corn field to evaluate performance and suitability under local conditions. The sensors performed according to manufacturers’ specifications, with accuracies of ±0.4 °C, ±1.4 °C, and ±0.3 °C for air-, soil-, and canopy-temperature measurements, respectively. Soil moisture sensors were calibrated and provided measurements within ±2 kPa of the manufacturer's values. Reliability of data collection and storage averaged 91%, with most bad or missing data occurring during periods of inclement weather and electrostatic interference. 相似文献
68.
Unpredictable rainfall, variations in farm inputs, crop-diseases, and the inherent potential of genotypes are among the major factors for low and variable crop yield. Fourteen elite groundnut genotypes were examined in 14 environments to analyze adaptability and stability of genotypes, and identify mega-environments if they exist. Additive main effect and multiplicative interaction (AMMI) model, cultivar-superiority measure, and genotype plus genotype-by-environment (GGE) biplot analysis were used for data analysis. The environment (69.8%) and genotype-by-environment interaction (GEI) effects (21.4%) were dominating the genotypic effect (8.8%). The GEI was significant (P < 0.01), and two distinct environments (mega-environments) were identified, suggesting separate national groundnut breeding strategies for Babile and Pawe. ICGV-94100 and ICGV-97156 were stable and had the highest-yield at Babile and Pawe, respectively. The higher heritability value was recorded in more homogeneous and favorable environments, indicating the genetic potential of groundnut genotypes were better attained in more homogeneous and favorable environments. AMMI model, cultivar-superiority measure, and GGE biplots were helpful methodologies and complemented each other to evaluate the adaptability and stability of groundnut genotypes in diverse environments. 相似文献
69.
Efrem Bechere David D. Fang Hirut Kebede Robert G. HardinIV Md. S. Islam Ping Li Jodi Scheffler 《Euphytica》2017,213(7):160
Cotton cultivars with reduced fiber-seed attachment force have the potential to be ginned faster with less energy. The objective of this study was to identify quantitative trait loci (QTL) for net ginning energy requirement (NGE), and its relationship with other fiber quality traits in upland cotton. Two cotton lines, TAM 182-34 ELS and AR 9317-26, with significant differences in NGE and fiber-seed attachment force, were crossed and 285 F2 plants derived from a single F1 plant were planted in the field and leaf samples collected for DNA marker analysis (Population A). Individual F3 plants and the two parents were planted in replicated progeny rows. The cotton was ginned on a 10-saw laboratory gin stand. Electrical power used by the gin was measured and recorded with a Yokogawa CW121 power meter. Fiber quality attributes were measured using a high volume instrument. A total of 455 SSR marker loci were used to construct a linkage map. Two QTLs were identified for NGE on chromosomes 12 and 20, associated with markers CIR148 and DPL0600, explaining 14 and 8.8% of the phenotypic variation, respectively. NGE shared the same genomic region with fuzz percent on chromosome 12. Population B, consisting of 260 F2 progeny from the reciprocal cross AR 9317-26 X TAM 182-34 ELS, was used to confirm these QTLs by analyzing SSR markers mapped on Chrs 12 and 20. These QTLs (qNGE-c12 and qNGE-c20) were confirmed and appeared stable. Further validation of significantly associated markers on different populations is necessary prior to implementation in marker-assisted selection. 相似文献
70.
Kebede Gezahagn Feyissa Fekede Assefa Getnet Alemayehu Mengistu Mengistu Alemayehu 《Journal of Crop Science and Biotechnology》2020,23(3):215-228
Journal of Crop Science and Biotechnology - Vetch is an annual forage legume and accessions of its species performed differently under different soil conditions. Twenty accessions of five vetch... 相似文献