农林科学最新文献

Atypical porcine pestivirus (APPV) is responsible for congenital tremor (CT) type A-II in pigs, a globally distributed neurological disease, with many unresolved questions regarding its pathogenesis and pathology. This descriptive case-control study assessed the viral load of APPV and its association with lesions in the central nervous system (CNS), as piglets born with severe clinical signs of CT recovered from clinical disease. The virus was found in all pigs with CT across 3 age groups (newborn, 3-week-old, 4- to 5-month-old CT pigs) using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The highest viral load was observed in the spinal cord of newborns and in the cerebellum of older groups. No APPV was detected in control pigs. Histologic evaluation revealed variable vacuolization in the CNS white matter of CT-affected pigs, which was most prominent in the spinal cord, cerebellum, and cerebrum of newborns, and in the cerebellum and cerebrum of 3-week-old pigs. Transmission electron microscopy demonstrated hypomyelination in newborn and 3-week-old CT pigs, but myelin levels comparable to those of control pigs in 4- to 5-month-old CT pigs. This research demonstrates the prolonged presence of APPV in the CNS of pigs born with severe signs of CT. Variable white matter vacuolization and hypomyelination can be found up to 3 weeks of age, but myelin levels normalize in older pigs, suggesting a delayed myelination process. Further research is needed to confirm the primary cellular target for APPV in the CNS and to understand how the virus affects the myelination process.

Microbiota composition represents a promising tool in precision farming, simultaneously serving as a benchmark of environmental challenge, a predictor of animal physiological status, and a direct target for host selection. In this paper, we compared the ability of microbiota composition and genomic information to predict swine performance in two production settings, namely a purebred nucleus (NU) and a terminal cross commercial population (TE). Microbiota consistently predicted all traits in both scenarios (NU-TE: training on NU to predict TE; TE-NU: training on TE to predict NU) and at two time points: mid-test and off-test. The highest correlation (i.e., prediction accuracy) was achieved for back fat, with values of 0.08 and 0.04, and 0.30 and 0.23 for mid and off-tests, predicting from nucleus to terminal, and vice versa. Similarly, daily gains correlations were 0.05 and 0.04, and 0.18 and 0.15 for the same time points and scenario combinations. Including genomic information yielded correlations ranging from low for loin area to moderate for back fat (0.19 nucleus to terminal, 0.16 for the opposite). Microbiota had higher prediction accuracies than genomic for back fat both from nucleus to terminal and vice versa (+0.11, +0.07) and daily gain (+0.08, +0.02) at off-test. Lower accuracies were obtained for the IMF. Including genomic and microbial information produced higher accuracies than microbiota or genomic alone for back fat (0.37 and 0.29 for nucleus to terminal and opposite) and daily gain (0.19 and 0.21 for nucleus to terminal and opposite). Results for other traits differed for different scenarios. Results show that microbiota composition effectively predicted most growth and carcass traits, particularly growth and fat deposition, across production systems, prediction scenarios (NU-TE and TE-NU), and time points (mid-test and off-test). These findings highlight the potential of microbiota profiles to predict phenotypes across production systems and support their use as a tool for selecting animals in environments they have not been exposed to.

Twin births in dairy cattle are rare but present significant challenges for animal welfare, as both the health of the cow and the calves are affected. This causes economic losses, which prompts breeders to select against twin births and identify associated risk factors. This study examines the phenotypic relationship between milk yield, fertility traits and twin births in German Holstein cattle using a large, population-wide dataset. GEBV correlations for twin births, milk production and fertility traits were estimated. Genome-wide association studies (GWAS) were conducted for calving numbers 1-3 in order to explore the genetic background in more detail. The twin birth rate showed a strong phenotypic association with milk production and a moderate phenotypic association with the timing of successful insemination. However, GEBV correlations were low: 0.04 with milk yield and -0.10 to 0.01 with fertility traits. GWAS revealed two potential candidate genes on BTA11: LHCGR and FSHR, which encode receptors for LH and FSH, two hormones crucial to estrus. In contrast to the first calving, significantly associated regions on BTA5 and BTA25 were found in calving numbers 2 and 3. This study demonstrates the interaction between genotype and environment, concluding that a genetic predisposition for twin births, in combination with a favourable endocrine state (environment), increases the likelihood of twin births.

Sedation is important for safe equine dental procedures, but it is unknown if there is a higher risk of sedation causing hypothermia in procedures performed during cold months. The authors hypothesize that sedation for a dental procedure will significantly decrease rectal body temperature in cold as compared to warm ambient temperatures. Adult equids (N = 246), from a private equine dentistry practice, that underwent dental equilibration, were selected for the study. Each horse's weight was estimated and sedation was administered intravenously (0.01 mg/kg detomidine and 0.01 mg/kg butorphanol) and intramuscularly (0.5 mg/kg xylazine and 0.03 mg/kg acepromazine). Ambient and serial rectal temperatures (presedation [PRE], 15 min after initial intravenous sedation [POST15], and at the end of the procedure [END]) were recorded. Statistics included Shapiro-Wilks test, Spearman's correlation coefficient, and a Friedman test with Dunn's posthoc test (significant at P < .05). Ambient temperatures ranged from -7.8 °C to 30 °C. The median (95% confidence interval) rectal temperature was PRE: 37.4 (37.2 °C-37.7 °C), POST15: 37.5 (37.2 °C-37.8 °C), and END: 37.4 (37.1 °C-37.7 °C). POST15 temperatures were significantly increased from PRE (P = .001) to END (P = .005) temperatures. PRE to END temperatures were not significantly different (P > .9). There was a weak positive correlation between ambient and POST15 temperatures (rho = .26, P < .001) and END temperatures (rho = .25, P < .001). Seven animals became hypothermic (<36 °C), only 2 at ambient temperatures below 4.44 °C. Rectal body temperature in equids after sedation at ambient temperatures between -7 °C and 30 °C remains at a safe level in most instances, suggesting dental procedures can be performed under sedation during cold weather.

Renal oxalosis has been reported in New and Old-World monkeys. Occasional reports describe a low prevalence of subclinical renal oxalosis, but these typically lack supporting evidence of primary oxalosis or toxicity and may be a natural background lesion. In a retrospective cross-sectional postmortem observation study, 12 of 156 (7.7%) African green monkeys (AGMs) (Chlorocebus sabaeus) from the Behavioural Science Foundation (St. Kitts) colony had histological evidence of oxalate-induced nephrosis (renal oxalosis). Histologically, affected tubules from both the cortex and medulla were ectatic; expanded several times normal size; and lined by attenuated, degenerative, regenerative, or necrotic epithelium with intraluminal, pale yellow, translucent, variably shaped, crystals that were birefringent under polarized light (calcium oxalate). The tubules were often surrounded by multinucleated macrophages. To identify independent predictors of renal oxalosis, we fit a multivariable logistic regression model with robust ("sandwich") standard errors, including sex, age, and birth origin, as categorical covariates. Several enrichment food items were found to be oxalate-rich: sweet potato (95.9 mg/100 g), pumpkin (64.6 mg/100 g), and bananas (169 mg/100 g). There was a significant increase in the prevalence of calcium oxalate concretions with age, from 0% in young monkeys to 18.6% in aged individuals, likely due to longer exposure to oxalate-rich produce and a cumulative effect. Due to the large ingestion of oxalate-rich foods, diet is suspected to be a major cause of subclinical oxalosis in the St. Kitts AGM, raising awareness of this potential background finding during their use as laboratory animals in toxicologic and other research studies.

Hepatic hemosiderosis has not been systematically studied in African green monkeys (Chlorocebus sabaeus). We aimed to determine the prevalence of histologic hepatic hemosiderosis in this species, demographic predictors of its presence and severity, and the quantitative relationship between histological grade and hepatic iron concentration. We evaluated liver samples of 155 African green monkeys from a research colony in St. Kitts (24 juveniles, 89 adults, 42 geriatrics) using histology (hematoxylin and eosin, Perls Prussian blue) to semiquantitatively grade (0-4) hemosiderin deposits. Quantitative hepatic iron was measured via coupled plasma mass spectrometry in 146 samples. Overall, 63.9% (99/155; P < .001 vs 50%) exhibited histological hemosiderin deposits. The grade distribution was 52 (33.5%) grade 0, 29 (18.7%) grade 1, 23 (14.8%) grade 2, 25 (16.1%) grade 3, and 26 (16.8%) grade 4. Wild-caught origin was protective (odds ratio (OR) = 0.10, 95% confidence interval (CI) = 0.04-0.29, P < .001), while geriatric age was associated with iron accumulation (OR = 8.92, 95% CI = 2.06-10.61, P = .003). Ordinal regression confirmed lower odds of higher grades in wild-caught (OR = 0.095, 95% CI = 0.047-0.193, P < .001) and higher odds of higher grades in adult monkeys (OR = 4.2, 95% CI = 1.43-12.35, P = .009). Trend tests (z = 9.81, P < .0001) and Spearman's ρ = 0.82 (P < .0001) confirmed a strong association between pathology and iron burden. Recommended iron requirements may be excessive for certain life stages in this species. Colony-born and younger animals are at highest risk, while adult males show protection. Histological grading correlates strongly with quantitative iron measures, validating its use as a semiquantitative surrogate.

Reducing the number of days from birth to slaughter is one strategy to improve animal feed and environmental efficiency. The export market use yearling sheep weighing 22-30 kg and usually purchases from large and small-scale traders at an early age (lambs weighing ≥ 15 kg) for mutton production. Hence, this study aimed to derive a new trait phenotype, which helps to reduce sheep market age without adverse effects on the market weight of Menz sheep and to evaluate the extent of exploitable genetic variation in this new trait. To this end, 11,258 lambs weighing ≥ 15 kg between 66 and 395 days of age were considered in this study. Co (variance) components and heritability estimates for novel traits were estimated using the average information restricted maximum likelihood method in WOMBAT fitting the animal model. The best-fitted model was selected from six models based on likelihood ratio test and Akaike's information criterion. The days-to-market weight of 16.3% of the animals was shorter by 48.2 days (with an estimated breeding value of -26.2 days) compared to the mean of the contemporary groups. The market weight of 15.5% of the animals was higher by 1.73 kg compared to the mean of the contemporary groups. There was a phenotypic variability of deviation in age at market weight (DAMW) and deviation in weight at market age (DWMA) for the sheep population in Molalie village compared to other villages. Likewise, the genetic standard deviation for DAMW and DWMA was 25 days and 0.79 kg, respectively. Based on the best-fitted model, the direct heritability estimate for DAMW and DWMA was 0.65 and 0.57, respectively. In addition, the maternal genetic effect explains 28% of the phenotypic variation in DAMW and 26% of the phenotypic variation in DWMA. The DAMW of Menz sheep in Dargegn and Molalie villages decreased significantly by 2.113 and 1.192 days year^-1, respectively. The observed additive genetic variance for DAMW suggests further scope for genetic improvement in the flock to reduce the days-to-market weight of Menz sheep. Including this novel trait in a breeding objective could shorten days to market weight without necessarily reducing the genetic merit of the live weight included in the breeding objective.

The present study examined correlated responses in commercial traits of economic importance resulting from selection for high growth over eight years in a population of red tilapia (Oreochromis spp.). During this period, data on total length, body colour and survival were recorded for 75,950 individual fish, which were progeny of 1203 dams and 608 sires. Our restricted maximum likelihood-mixed model analysis showed that selection for increased body weight produced concomitant positive changes in animal length by 3.1%. A correlated increase of 4.9% per generation was also observed for the survival rate in this population. Body hue colour, a trait of commercial interest, displayed a slight increase of 1.8% per generation. The substantial improvement in total length is consistent with the high genetic correlation (r_g) between body weight and length (r_g = 0.84). Body weight was weakly but significantly correlated genetically with the survival rate during the grow-out period from stocking to harvest. However, the genetic correlations between weight (or length) and body hue colour were not significant. Furthermore, there were substantial heritable genetic variations in these traits, with heritability estimates ranging from 0.12 to 0.36. Maternal and common full-sib effects accounted for 2.5%-17% of the total phenotypic variation. It is concluded that selection for increased body weight resulted in desirable correlated responses in complex quantitative traits of red tilapia, and these genetic characters will continue to respond to selection, given the substantial genetic variation in this red tilapia population.

The Montana Tropical cattle, a Taurine and Indicine composite, were developed in Brazil since 1994 and were based on crossing four biological types of cattle: zebu (mainly Nelore), tropical adapted taurine (mainly Senepol and Romosinuano), British taurine (mainly Angus) and continental taurine (as Charolais, Simental and Limousin). This study aimed to characterise the genetic ancestry of this composite breed at the genomic level. Principal component analysis revealed the composite in intermediate space between indicine and taurine but closer to the Taurine cluster, which is consistent with its multi-breed origin. The ADMIXTURE analysis indicated the Montana Tropical to be composed of several progenitor breeds without an indication of a dominant breed. Local ancestry analysis showed the Montana animals to have an average of 24% (standard deviation of ±5.41) Zebu ancestry. The total taurine ancestry was 62%, consisting of 19.6% (±6.96) from tropical adapted taurine, 20.1% (±5.99) from British taurine, 21.92% (±7.79) from continental taurine and 14% (±5.26) of the genome was undetermined. Based on the pedigree, these animals would have 20.8% ± 8.5% Zebu, 50.5% ± 14.4% tropical adapted taurine, 21.1% ± 13.5% British taurine and 7.6% ± 5.1% of continental European taurine in their composition. The genomic regions in the composite originating from each biological type highlight the trait complementarity each genetic group contributes. For example, the genomic region of high tropical adapted taurine ancestry was shown to harbour the slick hair locus, and the regions of high indicine ancestry are associated with high length of productive life. This study unravels the complex genetic ancestry of the Montana Tropical composite, highlighting the effective blend of ancestral gene pools that enhance key production and adaptation traits.