Effects of dietary calcium content and vitamin D source on skeletal properties in growing turkeys

1. The aim of the study was to investigate the effects of feeding fast growing turkeys with differentiated dietary calcium (Ca) content, and the partial replacement of vitamin D₃ in the feed with 25-hydroxycholecalciferol (25(OH)D₃), on skeletal properties.

2. One-day-old Big-6 male turkeys (n?=?1008) were randomly divided into 4 groups, and two subgroups were created within each group. The groups were differentiated with 4 levels of Ca provision in the feed, namely 85% of the National Research Council (NRC) recommendation (Group Ca₁); 95% as above (Group Ca₂); 105% as above (Group Ca₃); and 115% as above (Group Ca₄). The first subgroup received the recommended dosage of cholecalciferol (vitamin D₃ subgroup) in the feed, while in the second subgroup (Hy-D subgroup), half of the dosage of cholecalciferol was replaced with 25(OH)D₃. At the ages of 4, 8, 12 and 20 weeks, 7 turkeys from each subgroup were randomly selected and killed to obtain the right tibia for densitometric, geometric and mechanical analyses.

3. This study showed advantageous effects of increased calcium supply in the diet on skeletal system properties, that were increased and produced the most desirable traits in turkeys receiving 95%, 105% and 115% of the NRC calcium recommendation. Benefits resulting from administration of 25(OH)D₃ in the diet were also obtained in the skeletal formation of turkeys, and the most advantageous effects were present in the group receiving 105% of recommended dietary Ca.

4. Effects on the metabolic response of the skeleton of turkeys to manipulation of dietary calcium content and vitamin D₃ source were the most evident in the groups between 4 and 12 weeks of life, and demonstrated a limited ability to induce a positive influence on bone properties at advanced stages of the production cycle by alteration of these dietary factors.     

Genotype x environmental interaction for mature size and rate of maturing for Angus,Brahman, and reciprocal-cross cows grazing bermudagrass or endophyte infected fescue

Mature weight and rate of maturing were estimated in 177 Angus, Brahman, and reciprocal-cross cows grazing bermudagrass or endophyte-infected tall fescue over a 4-yr period to evaluate genotype x environment interactions. Data were collected every 28 d until cows were approximately 18 mo of age and then at prebreeding, postcalving, and weaning of calf. All cows with weight data to at least 42 mo of age were included in the analysis. Mature weight and rate of maturing were estimated using the three-parameter growth curve model described by Brody (1945). Data were pooled over year and analyzed by the general linear model procedure of SAS. Included in the models for mature weight and rate of maturing were the independent variables of genotype, environment, and genotype x environment interaction. There was a genotype x environment interaction (P < 0.01) for mature body weight (BW) but not for rate of maturing. Angus cows grazing fescue pastures had greater (P < 0.01) mean mature BW than Angus x Brahman cows grazing bermudagrass (611 +/- 17 vs 546 +/- 16 kg). Angus x Brahman cows grazing bermudagrass had lower (P < 0.05) mean mature BW than Brahman x Angus cows grazing bermudagrass or endophyte-infected fescue and Brahman cows grazing bermudagrass (546 +/- 16 vs 624 +/- 19, 614 +/- 22 and 598 +/- 20 kg, respectively). Brahman cows grazing endophyte-infected fescue had smaller (P < 0.05) mean mature BW than all genotype x forage combinations except for Angus x Brahman cows grazing bermudagrass. Angus cows had a smaller (P < 0.05) mean rate of maturing than Angus x Brahman and Brahman x Angus cows (0.039 +/- 0.002 vs 0.054 +/- 0.002 and 0.049 +/- 0.002%/mo, respectively), respectively, and Angus x Brahman cows had a larger (P < 0.05) mean rate of maturing than Brahman x Angus and Brahman cows (0.054 +/- 0.002 vs 0.049 +/- 0.002 and 0.041 +/- 0.002 %/mo, respectively). There was a direct breed x forage interaction (P < 0.05) for mature BW. These data suggest that the choice of breed type is important in maintaining a crossbreeding program, in that mature BW and rate of maturing are critical to the matching of animal requirements to available production resources.     

A physiologically based pharmacokinetics model for florfenicol in crucian carp and oral‐to‐intramuscular extrapolation

Yang, F., Sun, N., Sun, Y. X., Shan, Q., Zhao, H. Y., Zeng, D. P., Zeng, Z. L. A physiologically based pharmacokinetics model for florfenicol in crucian carp and oral‐to‐intramuscular extrapolation. J. vet. Pharmacol. Therap.  36 , 192–200. In this study, an oral physiologically based pharmacokinetics (PBPK) model was developed for florfenicol in crucian carp (Carassius auratus). Subsequently, oral‐to‐intramuscular extrapolation was performed and the two models were used to predict florfenicol concentrations in the edible tissues of crucian carp. The oral model gave good predictions in most tissues, except for kidney and liver in which the florfenicol concentrations were underestimated at the later time points. In contrast, using the intramuscular model, the concentrations in the kidney were overestimated at the later time points. Both models had the best predictive ability in the main edible tissue, the muscle. The oral model also accurately predicted the florfenicol concentrations in the muscle after multiple doses. The present study demonstrated the feasibility of predicting florfenicol concentrations in the edible tissues of crucian carp using a route‐to‐route extrapolation method.     

Neutrophil apoptosis during the resolution of bovine mammary gland injury

The role of neutrophil apoptosis in the resolution of bovine mammary gland injury induced by intramammary administration of physiological buffered saline (PBS) or lipopolysaccharide (LPS) was investigated. Twenty mammary glands of five non-pregnant heifers were used in the two studies and each animal received both stimuli. Samples of cell populations were collected by mammary gland lavages before and 24, 48, 72 and 96 hours after treatment and examined by light microscopy and staining for myeloperoxidase (MPO). A marked influx of neutrophils into the mammary gland was observed 24 hours after stimulation. At the same time, apoptotic neutrophils and MPO-positive macrophages (MAC) were identified in the samples. The numbers increased to reach maximum values at 48 hours after stimulation with PBS and at 72 hours after stimulation with LPS. The observed differences in the length of the resolution period indicate that neutrophil viability can be modulated by delaying the apoptotic process. Apoptosis of neutrophils and their subsequent phagocytosis by MAC can be regarded as a significant mechanism in the removal of neutrophils from the acutely injured mammary glands and, hence, in the resolution of bovine mastitis.     

Endoscopic examination of snakes by access through an air sac

Sixteen boa constrictors (Boa constrictor), three royal pythons (Python regius) and 15 Burmese pythons (Python molurus bivittatus) were examined endoscopically by access through the air sac. The snakes were immobilised in a ventral position using a half-open anaesthetic system with assisted ventilation and a mixture of isoflurane and oxygen. The rigid endoscope was introduced percutaneously and the internal structure of the lungs and the air sac, and the shape, size and external surface of the liver were visible in the cranial direction. In the smaller snakes the bifurcation and caudal part of the trachea could be viewed, provided the endoscope was positioned in a retrograde orientation. The caudal orientation of the endoscope made it possible to view the gall bladder and the size, shape and surface of the spleen. In some cases, the pancreas and the surface of the stomach and colon could be monitored. Endoscopy through the air sac also made it possible to check the major veins in the coelom. The snakes were monitored for at least 30 days after the intervention and no changes in their respiratory function or general health were observed.     

对FC株猪源性肠毒素型大肠杆菌致病因子的研究

FC菌株是一株从腹泻仔猪粪便中分离的肠毒素型大肠杆菌(Enterotoxigenic E.coli,ETEC)。在MRHA反应中,本菌能凝集人O型、豚鼠、马、绵羊、牛、鸡和兔的红细胞,对人O型和豚鼠红细胞有很高的血凝性,血抗K88和K99血清不能抑制其对豚鼠和绵羊红细胞的血凝。在体外小肠上皮细胞吸附试验中,本菌对仔猪小肠上皮细胞具有强烈的吸附作用;透射电镜和扫描电镜观察证实了FC株菌除表面具有一种纤毛样结构外,还能定居在仔猪小肠段。血清学试验结果表明,本菌的O抗原属于O101。K88和987P两种抗血清均不能凝集本菌,而K99和F41抗血清均可凝集。对纯化的FC株菌粘着素抗原作等电聚焦和聚丙烯酰胺凝胶电泳分析,结果表明,该菌的粘着素是由等电点分别为4.61和9.78,分子量分别为29500和17500的两种蛋白质抗原所组成。此外,用乳鼠胃内投服试验和兔肠结扎试验证明,该菌只产生热稳定肠毒素。总之,本菌是一株能产生ST的K99,F41的肠毒素型大肠杆菌。