Relationships between the first ovulation postpartum and polymorphism in genes relating to function of immunity, metabolism and reproduction in high-producing dairy cows

The decrease in fertility and conception rates of high-producing dairy cows is one of the major negative impacts for today's producers. The recovery of ovarian activity postpartum is affected by the status of immunity, metabolism and reproduction and plays a critical role in subsequent fertility after parturition in the cow. In the present study we investigated the relationships between polymorphisms in genes relating to the above functions and the first postpartum ovulation as a marker of the recovery of ovarian function in the cow. In immune function related-factors, the occurrence of first postpartum ovulation within 3 weeks in the C/C genotypes of tumor necrosis factor α (TNFα) exon (55.4%) and the A/G genotypes of TNFα promoter (55.4%) was significantly higher than that in T/T genotypes of TNFα exon (14.3%) and A/A genotypes of TNFα promoter (14.3%). Moreover, anovulatory cows with the T/T genotype of TNFα exon and the A/A genotype of TNFα promoter tended to have a prolonged days open compared with those of the other genotypes of TNFα polymorphisms. In metabolic function-related factors, ovulatory and anovulatory cows had a different distribution for alleles of the growth hormone receptor, but there were no significant differences in genotype and allele frequency of insulin-like growth factor-I polymorphism. No significant relationships were found between ovarian function after parturition and polymorphisms for reproduction-related genes. In conclusion, polymorphisms of TNFα gene both in exon and promoter regions have a strong association with the early first ovulation within 3 weeks after parturition in the high-producing dairy cow. Taken together, polymorphisms of TNFα gene could be strongly related to early first ovulation after parturition, thus being an effective tool of selection for improving reproductive performance in the high-producing dairy cow.     

Mead acid supplementation does not rescue rats from cataract and retinal degeneration induced by N-methyl-N-nitrosourea

Fatty acids and their derivatives play a role in the response to ocular disease. Our current study investigated the effects of dietary mead acid (MA, 5,8,11-eicosatrienoic acid) supplementation on N-methyl-N-nitrosourea (MNU)-induced cataract and retinal degeneration in Sprague-Dawley rats. Experiment 1 was designed to inhibit cataract formation, with the dams fed a 2.4% MA or basal (<0.01% MA) diet during lactational periods. On postnatal day 7, male pups received a single intraperitoneal (ip) injection of 50 mg/kg MNU or vehicle. Lens opacity and morphology were examined 7 and 14 days after the MNU injection. Experiment 2 was designed to inhibit retinal degeneration and was performed with female postweaning rats. In this experiment, dams were fed the 2.4% MA or basal diet during the lactational periods. Thereafter, the female pups were continuously fed the same diets during their postweaning periods. On postnatal day 21 (at weaning), pups received a single ip injection of 50 mg/kg MNU. Retinal morphology was examined 7 days after the MNU injection. In experiment 3, six-week-old female rats were fed the 2.4% MA or basal diet starting at one week before the MNU injection and were then continuously fed the same diets until sacrifice. Rats at 7 weeks of age were given a single ip injection of 40 mg/kg MNU, and the retina was then examined morphologically one week after the MNU injection. In experiment 1, mature cataract was found in all of the MNU-treated groups, with or without MA supplementation. In experiments 2 and 3, atrophy of both the peripheral and central outer retina occurred in all rats exposed to MNU, with or without MA supplementation, respectively. The severities of the cataracts and retinal atrophy in the rats were similar regardless of MA supplementation. Dietary mead acid, which is used as a substitute in essential fatty acid deficiency in the body, does not modify MNU-induced cataract and retinal degeneration in rat models.     

Derived muscle arrangements and their shared innervation patterns of external and internal cheek pouches in rodents

Cheek pouches have evolved from the oral cavity in rodents and act as temporary food storage repositories. There are two types of opening, internal and external. Details about the complex cutaneous muscles controlling the pouches have still not been fully elucidated. To understand the shared and derived traits of the muscles surrounding the cheek pouch and their innervation, we carried out an evolutionary morphological study using two desert kangaroo rats (Dipodomys deserti) and three plains pocket gophers (Geomys bursarius) from each of the two families equipped with external cheek pouches, and four Syrian hamsters (Mesocricetus auratus) with internal cheek pouches. The most conspicuous derived trait of the muscles between the external and internal cheek pouches, the sphincter sacculi, surrounds almost all of the edge of the outer entrance of the pouch. It is present in both species with external pouches, but not in hamsters, which have internal pouches. Our neurological findings demonstrate that most pouch muscles are innervated by both the facial and the cervical nerves, regardless of the pouch type. In these dually innervated muscles, the ventromedial part of the muscles tends to be innervated dominantly or uniquely by the cervical nerves, which usually enter from the superficial or lateral aspect. As a trait shared with the cervical nerves innervating the propatagial muscles in aerodynamic mammals such as bats and flying squirrels, and panniculus carnosus in most mammals, our neurological evidence suggests that the cervical nerve has the potential to innervate derived cutaneous muscles in the cervicofacial region.     

Production of lipid mediators in mastitic milk of cow

Bovine mastitis is one of the most prevalent and costly diseases in the dairy industry. Lipid mediators are signaling molecules which coordinately and intricately modulate inflammation. They are produced from polyunsaturated fatty acids (PUFAs) in the cellular membrane via several enzymes including cyclooxygenase (COX) and lipoxygenase (LOX). In the present study, we performed comprehensive analysis of lipid production in milk obtained from clinical or subclinical mastitic cows using liquid chromatography/mass spectrometry. We detected 26, 24, and 40 kinds of lipid constantly in healthy, subclinical, and clinical mastitic milk, respectively. In clinical mastitic milk, the amount of a major n‐6 PUFA, arachidonic acid (AA), tended to increase, whereas amounts of major n‐3 PUFAs, eicosapentaenoic acid and docosahexaenoic acid, tended to decrease. The amounts of several AA‐derived lipids including COX‐catalyzed prostaglandin (PG) D₂ and PGE₂, and LOX‐catalyzed leukotriene (LT) B₄ were increased in clinical mastitic milk. Although subclinical mastitic milk represented similar trend of lipid production to healthy milk, amounts of several lipids such as LTD₄, 14,15‐dihydroxyeicosatrienoic acid, and 14‐epoxyeicosatrienoic acid changed. These findings would be helpful for better understanding of mastitis pathology and give us some insights to develop a new diagnostic and therapeutic strategy.     

Effects of physically effective fiber in diets based on rice straw and cassava pulp on chewing activity,ruminal fermentation,milk production,and digestibility in dairy cows

The objective of this study was to evaluate the effects of physically effective neutral detergent fiber (peNDF) in rice straw and cassava pulp diets on the chewing activity, ruminal fermentation, milk production, and digestibility in low‐producing dairy cows. Eight lactating Holstein crossbred cows were randomly divided into two groups in a crossover design with two dietary treatments over two 21‐day periods. The difference in peNDF contents was achieved by balancing the ratio of rice straw, cassava pulp, and concentrate. The high cassava pulp diet had 15.5% peNDF and the low cassava pulp diet had 20.2% peNDF. The results showed that feeding the low cassava pulp diet increased the concentrations of milk protein, milk fat, solids‐not‐fat, and total solids in the milk. In contrast, the dry matter intake, milk yield, lactose content, chewing activity, nutrient digestibility, ruminal fermentation, and pH were not affected by treatments.     

Astaxanthin Z-isomer-rich diets enhance egg yolk pigmentation in laying hens compared to that in all-E-isomer-rich diets

The effects of feeding diets containing astaxanthin with different Z-isomer ratios to laying hens on egg qualities, such as astaxanthin concentration in egg yolk and yolk color, were investigated. As the astaxanthin source, a natural microorganism Paracoccus carotinifaciens was used. Astaxanthin with different Z-isomer ratios was prepared by thermal treatment with different conditions and then added to the basal diet at a final astaxanthin concentration of 8 mg/kg. We found that, as the Z-isomer ratios of astaxanthin in the diet increased, the astaxanthin concentration in egg yolk and the yolk color fan score also increased significantly. Importantly, feeding a 50.6% Z-isomer ratio diet increased astaxanthin concentration in egg yolk by approximately fivefold and the color fan score by approximately 2 compared to that in hens fed an all-E-isomer-rich diet. Moreover, we showed that feeding Z-isomer-rich astaxanthin to laying hens increased plasma astaxanthin concentration by more than five times in comparison to that in hens fed an all-E-isomer-rich diet. These results indicate that Z-isomers of astaxanthin have higher bioavailability than that of the all-E-isomer and thus they exhibit greater egg yolk-accumulation efficiency.     

Serotyping of Mannheimia haemolytica isolates from bovine pneumonia: 1987-2006

Over a period of 20 years, a total of 207 Mannheimia haemolytica samples were isolated from calves affected with pneumonic pasteurellosis and serotyped by the indirect haemagglutination test. Serotypes A1 (102 isolates), A2 (47 isolates) and A6 (42 isolates) were most common; in addition, 16 isolates were serotypes A7, A13, A14 or untypable. The relative prevalence of serotype A6 has increased recently in Japan, as has been reported from other countries. The results of this study provide useful information towards the design of efficient vaccines for the prevention of M. haemolytica infection in Japan.     

Impact of metritis on the generation of reactive oxygen species by circulating phagocytes and plasma lipopolysaccharide concentration in peripartum dairy cows

This study examined the relationship between postpartum metritis, reactive oxygen species (ROS) generation, and plasma lipopolysaccharide (LPS) concentration in peripartum dairy cows. Blood was collected twice weekly from 2 weeks prepartum through 6 weeks postpartum. Whole blood chemiluminescence (WBCL) was measured using the luminol‐enhanced zymosan‐stimulated chemiluminescence assay. Cows were examined for uterine health disorders and classified into two groups, healthy (n = 11) and metritis (n = 5). Metritis had a significant effect on WBCL, with cows with metritis having a higher WBCL. Plasma LPS concentrations in cows with metritis were significantly higher than in healthy cows. To examine the effect of LPS on WBCL, blood was sampled in healthy peripartum cows (1 to 2 weeks prepartum, n = 8; 0 to 3 weeks postpartum, n = 11; and 4 to 8 weeks postpartum, n = 8) and incubated with LPS. At 1 endotoxin units/mL of LPS, similar to the plasma LPS concentration in cows with metritis, the WBCL increased in cows at 0 to 3 weeks postpartum. Results indicate that the increase in ROS generation and plasma LPS concentration are associated with metritis, and LPS may be responsible for enhanced ROS generation in early postpartum dairy cows.     

Morphological Characteristics of the Temporomandibular Joint in the Pouch Young of the Tasmanian Devil

We recently reported the absence of the articular disc, which is a constant structure in mammals, in the temporomandibular joint of the adult Tasmanian devil. However, whether the articular disc disappears with growth of the animal was unknown. The aim of this study was to determine whether a pouch young of the Tasmanian devil has the articular disc. The temporomandibular joint of a fresh carcass of the pouch young, whose crown–rump length was 43 mm, was examined microscopically and by microcomputed tomography. The absence of the articular disc in the pouch young temporomandibular joint was histologically confirmed. It is suggested that the articular disc of the Tasmanian devil is naturally absent.