Pharmacokinetics of ivermectin in the yak (Bos grunniens)

The yak (Bos grunniens) belongs to the cattle family Bovidae and lives in the mountains of China and adjacent areas. Due to the physiological adaptations of yak to its environment and the lack of data, the ivermectin pharmacokinetic was studied following a single subcutaneous dose at the recommended dose for cattle (0.2 mg kg(-1)). The observed peak plasma concentration (Cmax) was 48.93 ng ml(-1) and the time to reach Cmax (Tmax) was 0.73 day. These results show a faster rate of absorption than in cattle. The values for the absorption half-life (t(1/2a)), the distribution half-life (t(1/2alpha)) and the terminal half-life (t(1/2beta)) were 0.31, 0.74 and 4.82 days, respectively. The calculated area under the concentration-time curve (AUC) was 146.2 ng day ml(-1) and the mean residence time (MRT) was 3.57 days. The availability of ivermectin appears low in yaks in comparison to cattle but equivalent to that reported in horses and is likely to be due to physiological characteristics of this species.     

The cranial cervical ganglion and its branches in the yak (Bos grunniens)

The heads and necks of 10 yaks were dissected to study the shape, location, arrangement, and branches of the cranial cervical ganglion. The ganglion was a greyish fusiform structure, mean length 19.72 mm, width 7.65 mm and depth 4.55 mm, located on the rostrolateral surface of the m. longus capitis. Approximately 25% of the ganglion was covered by the tympanic bulla, the rest by the m. stylohyoideus. The branches of the cranial cervical ganglion included the internal and external carotid nerves, sympathetic trunk and the branches connecting with the glossopharyngeal, vagus and hypoglossal nerves. In one animal the right cranial cervical ganglia was a greyish pyramidal structure 10 mm long, 8 mm wide and 5 mm thick but the left ganglion was similar to those found in the other specimens examined.     

The cranial cervical ganglion and its branches in the White yak (Bos grunniens)

The heads of 12 White yaks (four castrated, four male and four female, 3-8 years old) were dissected to study the shape, location and branches of the cranial cervical ganglion macroscopically. The ganglion was a greyish arciform structure, with a mean length of 17.3 mm, a width of 8.0 mm and a thickness of 3.9 mm, located on the rostrolateral surface of m. longus capitis. Approximately 5% of the ganglion was covered laterally by the tympanic bulla and the rest by the m. stylohyoideus. The branches of the cranial cervical ganglion included the internal and external carotid nerves, the sympathetic trunk and communicating branches to the glossopharyngeal nerve, the pharyngeal branch of the vagus nerve and the hypoglossal nerve. In one specimen, the left cranial cervical ganglion was fusiform and only covered by the m. stylohyoideus. Gender differences of the cranial cervical ganglion in the White yak were not observed.     

Expression characteristics of immune factors in the yak (Bos grunniens) testis

The goal of this study was to characterize and evaluate the main markers of macrophages, T lymphocytes, B lymphocytes and plasmocytes in the testis of juvenile and adult yaks by quantitative real-time polymerase chain reaction and immunohistochemistry. Within the same age group, the mRNA expression of CD68 was always highest, followed by that of CD3ε, CD79α, IgG and IgA. Moreover, CD68, CD3, CD79α, IgA and IgG positive cells were all located in the testicular interstitial tissues of juvenile and adult yaks. In the same age group, the frequency of CD68 positive macrophages was higher than that of CD3 positive T lymphocytes, which was followed by that of CD79α positive B lymphocytes and IgA and IgG positive plasmocytes. No significant difference was observed between the B lymphocyte and plasmocyte frequencies in yak testes. Furthermore, CD68, CD3ε, CD79α, IgA and IgG mRNA expression levels and the frequencies of CD68, CD3, CD79α, IgA and IgG positive cells increased from juveniles to adults. Similarly, the frequencies of CD68, CD3, CD79α, IgA and IgG positive cells also increased with age. These results suggest that in the yak testis, the immune defence system against pathogens might primarily comprise macrophages and T lymphocytes in the testicular interstitial tissue. Moreover, the testicular immune environment may mature and expand to a fully functional state in adult yaks. The low frequencies of B lymphocyte and plasmocyte in yaks, differing from those in rodents and humans, might be related to the fact that yaks live in low-oxygen plateaus.     

中国牦牛的血液蛋白多态与聚类分析

根据牦牛血液蛋白多态性,利用系统聚类方法对中国11个类群的牦牛进行聚类分析,结果表明,中国牦牛大致分为北方型和西部型,西部型又可分为青藏高原亚型和横断高山亚型;另外,中国牦牛血缘较近,起源单一,血液蛋白多态性相对贫乏,基因趋于纯合。     

Milk protein polymorphisms in cattle (Bos indicus), mithun (Bos frontalis) and yak (Bos grunniens) breeds and their hybrids indigenous to Bhutan

In the current study, milk protein variation was examined in cattle (Bos indicus), mithun (Bos frontalis), yak (Bos grunniens) and their hybrid populations in Bhutan to estimate genetic variability, conduct genetic characterization and assess the possibility of gene flow between mithun and cattle. Isoelectric focusing of 372 milk samples from 11 populations detected four molecular types of β‐lactoglobulin (A, B, E and M), five molecular types of α_S1‐casein (A, B, C, E and X) and three molecular types of k‐casein (A, B and X). Mithun and yak shared alleles but were found to exhibit different allele frequencies for the proteins studied. The degree of genetic variability within populations was measured by average heterozygosity and ranged from 24–40% in cattle, 26% for yak and 33% for mithun. We also resolved the traditional mithun and cattle hybridization system via principal component analysis. Our results suggested secondary introgression of mithun genes to the village Thrabum population, and a close genetic relationship between Bhutanese indigenous cattle and Indian cattle.     

Anesthesia of Tibetan yak (Bos grunniens) using thiafentanil - xylazine and carfentanil - xylazine

The use of 0.025 +/- 0.012 mg/kg (median +/- interquartile range) thiafentanil with 0.15 +/- 0.03 mg/kg xylazine (TX) and 0.011 +/- 0.0015 mg/kg carfentanil with 0.25 +/- 0.093 mg/kg xylazine (CX), with dosages based on estimated bodyweight, was used in the anesthesia of 37 Tibetan yak (Bos grunniens) housed within a drive-through animal park setting. The median time to lateral recumbency was 5 and 7 min for each group, respectively. With the addition of propofol in 8 CX animals and 17 TX animals, the anesthetic plane was suitable for a wide range of procedures. The median time to standing recovery following administration of naltrexone was 4 +/- 3.5 min with TX and 7 +/- 1.5 min with CX. There was one fatality and one case of renarcotization in the TX group. Overall, the dosages used in the study provided a reliable and useful anesthetic induction protocol, with TX animals demonstrating a more rapid induction and recovery with less cardiac depression than CX animals.     

The expression of hypoxia-inducible factor-1 alpha in primary reproductive organs of the female yak (Bos grunniens) at different reproductive stages

The yak (Bos grunniens) is the most important livestock animal in high-altitude regions owing to its prominent adaptability to cold conditions, nutritional deficiencies and hypoxia. The reproductive organs exhibit different histological appearances and physiological processes at different reproductive stages. Hypoxia-inducible factor-1 alpha (HIF-1α) is the regulatory subunit of HIF-1 that crucially regulates the response to hypoxia in mammalian organisms. The goal of our study was to investigate the expression and distribution of HIF-1α in the primary yak reproductive organs at different reproductive stages. Samples of the ovary, oviduct and uterus of 15 adult female yaks were collected and used in the experiment. The expression and localization of HIF-1α proteins and mRNA were investigated using quantitative real-time polymerase chain reaction (qRT-PCR), Western blot (WB) and immunohistochemistry (IHC). The results indicated that the expression of HIF-1α protein in the ovary was higher during the luteal phase than during the follicular phase and gestation period (p < .05). In the oviduct, HIF-1α protein was also more highly expressed during the luteal phase than during the follicular phase and gestation period (p < .01). However, in the uterus, the HIF-1α protein had stronger expression during the gestation period than during the follicular phase (p < .01) and luteal phase (p < .05). The expression of HIF-1α mRNA was similar to that of its protein. Immunohistochemical analysis revealed intense immunostaining of HIF-1α proteins in the follicular granulosa cells, granular luteal cells, villous epithelial cells of the oviduct, endometrial glandular epithelium and luminal epithelium, foetal villous trophoblast, and epithelia of caruncular crypts. This study showed that the expression of HIF-1α in the ovary, oviduct and uterus varies according to the stage of the reproductive cycle. This implies that HIF-1α plays an important role in regulating the stage-specific physiological function of yak reproductive organs under hypoxic environments.     

The microanatomy of the palatine tonsils of the buffalo (Bos bubalus)

The palatine tonsils play a key role in initiating immune responses against antigens entering the body through the mouth. They are also replication sites of some pathogens. There is no data available about the structure of the palatine tonsils of the Egyptian water buffalo. Therefore, palatine tonsils of 14 clinically healthy buffalo bulls (2–3 years old) were examined macroscopically and microscopically using light, and transmission electron microscopes. The tonsils had an elongated kidney shape with a central invagination (tonsillar fossa) containing a single macroscopic opening leading to a small central cavity (tonsillar sinus). A number of macroscopic crypts originated from this sinus (internal crypts). Besides the tonsillar fossa, also small macroscopic crypts (external crypts) were present. The tonsils were enclosed by a thin connective tissue capsule and septa divided the tonsils into incomplete lobes. Within these encapsulated organs mucous glands were very obvious. Each crypt was highly branched and lined with stratified squamous non-keratinized epithelium. Several lymphoid cells infiltrated between the epithelial cells forming patches of lymphoepithelium. The crypt lumen contained lymphocytes, neutrophils and erythrocytes. Lymph nodules with clear germinal centers extended under the epithelial surface. Diffusely distributed lymphocytes were found in the narrow interfollicular region. High endothelial venules, interdigitating dendritic cells, macrophages and plasma cells were observed among the diffuse lymphocytes. Lymphatics filled with lymphocytes drained the tonsils.     

牦牛与黄牛远缘杂种雄性不育的研究现状及对策

黄牛和牦牛远缘杂交后代雌性不育是生物界种属间遗传隔离的现象之一。本文系统地论述了各个学科对犏牛雄性不育的研究概况，并根据存在的问题提出了研究犏牛雄性不育遗传机理及其克服的可能途径。同时探讨了应用染色体减数分裂联会复合体，染色体标记同工酶和ＤＮＡ多态检测等技术，研究牦牛和黄牛远缘杂交后代雄性不育与可育遗传机理的可能性。     

Protein and mRNA expression of follicle‐stimulating hormone receptor and luteinizing hormone receptor during the oestrus in the yak (Bos grunniens)

Follicle‐stimulating hormone (FSH) and luteinizing hormone (LH) have a central role in follicle growth, maturation and oestrus, but no clear pathway in the seasonal oestrus of yak (Bos grunniens) has been found. To better understand the role of FSH and LH in seasonal oestrus in the yak, six yaks were slaughtered while in oestrus, and the pineal gland, hypothalamus, pituitary gland, and gonads were collected. Using real‐time PCR and immunohistochemical assays, we determined the mRNA and protein expression of the FSH and LH receptors (FSHR and LHR) in these organs. The analysis showed that the FSHR mRNA expression level was higher in the pituitary gland tissue compared with LHR (p < .01) during oestrus. By contrast, there was low expression of FSHR and LHR mRNA in the pineal gland and hypothalamus. FSHR mRNA expression was higher than that of LHR (p < .05) in the ovary, whereas LHR mRNA expression was higher than that of FSHR (p < .01) in the uterus. FSHR and LHR proteins were located in the pinealocyte, synaptic ribbon and synaptic spherules of the pineal gland and that FSH and LH interact via nerve fibres. In the hypothalamus, FSHR and LHR proteins were located in the magnocellular neurons and parvocellular neurons. FSHR and LHR proteins were localized in acidophilic cells and basophilic cells in the pituitary gland, and in surface epithelium, stromal cell and gland epithelium in the uterus. In the ovary, FSHR and LHR protein were present in the ovarian follicle. Thus, we concluded that FSHR and LHR are located in the pineal gland, hypothalamus, pituitary and gonad during oestrus in the yak. However, FSHR was mainly expressed in the pituitary gland and ovaries, whereas LHR was mainly expressed in the pituitary gland and uterus.     

Spermatogenesis in Bali cattle (Bos sondaicus) and hybrids with Bos indicus and Bos taurus

Semen quality, testis size and efficiency of sperm production in Bali cattle (Bos sondaicus) and hybrids with Bos indicus and Bos taurus were determined. Mean (+/- SEM) daily sperm production per gram of testis parenchyma (DSPG) in six purebred Bali bulls was 12.2 +/- 0.7 x 10(6). F1 B sondaicus cross B taurus bulls and F1 B sondaicus cross B indicus bulls were sterile. Spermatogenesis was arrested at the late primary spermatocyte stage. In 11 B sondaicus cross B indicus crosses, mean DSPG was lower than in the purebred B sondaicus, although four (one 1/4 B sondaicus, one 3/4 B sondaicus, one 5/8 B sondaicus inter se and one 3/8 B sondaicus inter se) exhibited DSPG levels similar to the foundation stock. Semen from those crossbreeds which exhibited complete spermatogenesis was more variable in terms of spermatozoal concentration, percentage of spermatozoa exhibiting progressive motility and levels of spermatozoal abnormalities. In crossbreeds where sperm production was reduced or absent, there was seminiferous epithelial dysfunction, manifested as an increased frequency of degenerative late pachytene and diplotene primary spermatocytes and germinal cells occurring later in the cycle, or in extreme cases, as complete arrest of spermatogenesis at the late primary spermatocyte stage.     

Enzymatic characteristics of crude feruloyl and acetyl esterases of rumen fungus Neocallimastix sp. YAK11 isolated from yak (Bos grunniens)

Rumen fungus Neocallimastix sp. YAK11 was isolated from yak (Bos grunniens), and three consecutive 10‐day pure cultures were anaerobically performed at 39 °C in 20‐ml Hungate’s tubes to explore ferulic acid esterase (FAE) and acetyl esterase (AE) activity profiles of the fungus grown on whole hay fraction of Chinese wildrye grass (Leymus chinensis) (WHO_cw, n = 4) and its neutral detergent fibre fraction (NDF_cw, n = 4), respectively. An aliquot of 0.7‐ml culture was sampled daily using a sterile syringe, and 0.7‐ml fresh medium was immediately added to the tubes to compensate for the withdrawn samples. Peak esterase activity occurred for FAE on day 5 (p < 0.001) and for AE on day 6 (p < 0.001). The mean activities of FAE and AE in WHO_cw were 2.07 and 1.29 times of those in NDF_cw (p < 0.001). Both FAE and AE activities were positively correlated with xylanase (r > 0.65, p < 0.001) and carboxymethyl cellulase (r > 0.57, p < 0.001) activities. Total volatile fatty acid concentration was positively correlated with enzyme activities of AE (r > 0.87, p < 0.001), FAE (r > 0.82, p < 0.001) and xylanase (r > 0.56, p < 0.001). Crude enzyme solution was harvested for the fungus grown on WHO_cw, and the pH optimum of FAE activity was 8.0 while the optimum for AE was 9.0. Both FAE and AE had a broad pH stability range. The optimal temperatures for FAE and AE activity were 40 and 50 °C. The Michaelis constant (K_m) and maximum velocity (V_max) for FAE against methyl ferulate at pH 6.0 and 39 °C were 0.078 mm and 2.93 mU, respectively. The K_m and V_max for AE against p‐nitrophenyl acetate at pH 7.0 and 39 °C were 2.73 mm and 666.67 mU, respectively. Both FAE and AE may have prospective advantages for the enzymatic degradation of roughages in ruminant animals.     

The arterial supply of the navicular bone in the normal horse

An arteriographic and histological study of the arterial blood supply of 35 navicular bones, from 19 adult horses with no clinical or radiographical signs of navicular disease, is described. The arteries enter the navicular bone from four directions: distal, proximal, medial, and lateral. The navicular bone can be divided into areas which receive arteries from one, two, or three directions, whereas the distal supply covers the largest part of the navicular bone. The distal arteries enter the navicular bone through the nutrient foramen which contains loose connective tissue, nutrient vessels and myelinated nerves. At least 77 per cent of the nutrient foramina contains synovial membrane. Twelve per cent of the arteries in the navicular bone show histological changes. Thickening of the intima with or without splitting of the internal elastic membrane and hyalinization, fibrosis and hypertrophy of the media were observed.     

Differences in copper and selenium metabolism between Angus (Bos taurus) and Brahman (Bos indicus) cattle

A 2-yr study was conducted at the Range Cattle Research and Education Center, University of Florida – Institute of Food and Agricultural Sciences (IFAS) (Ona, FL), to evaluate differences in the metabolism of Cu and Se of Angus (Bos taurus) and Brahman (Bos indicus) cattle. Thirty-two pregnant beef cows (n = 8 Brahman and 8 Angus/yr) were enrolled in the study in the first trimester of gestation. This study consisted of three phases: 1) restriction (day 0 to 90), 2) supplementation (day 91 to 150), and 3) calving. During all three phases, cows were individually fed and housed in partially covered drylot pens. During the restriction and supplementation phases, cows were provided a 1.5 kg/d of a grain-based concentrate supplement, which was fortified with flowers of S (50 g of supplemental S/cow daily; restriction phase) or Cu and Se (100 and 3 mg/d of Cu and Se, respectively; supplementation phase). Blood and liver samples were collected from all cows at 30 d intervals and from both cows and calves within 24 h of calving. Colostrum and milk samples were collected at calving and 7 d after birth. All data were analyzed using the MIXED procedure of SAS, where cow and calf were the experimental unit. During the restriction phase, a breed × day effect (P = 0.03) was observed where Brahman had greater liver Cu concentration than Angus cows in all sampling days. For liver Se concentration, a tendency (P = 0.07) for a breed effect was observed where Angus cows tended to have greater liver Se concentration than Brahman. During the supplementation phase, breed (P < 0.001) and day (P < 0.01) effects were observed, where Brahman cows had greater liver Cu concentration than Angus. For liver Se concentration, a day effect (P < 0.001) was observed, where liver Se concentration increased (P < 0.001) from day 90 to 120 and remained unchanged (P = 0.86) until day 150. At calving, no effects of breed (P = 0.34) were observed for liver Cu concentration of cows; however, Brahman calves tended (P = 0.09) to have greater liver Cu concentration than Angus calves. For Se liver concentration at calving, Angus cows tended (P = 0.07) to have greater liver Se concentration than Brahman cows; however, no breed differences (P = 0.70) were observed for liver Se concentration of calves at birth. In summary, substantial differences in multiple indicators of Cu and Se status were observed between Angus and Brahman cattle, implying that Angus and Brahman cattle possibly have different mechanisms to maintain adequate Cu and Se status.