Genetic potential for residual feed intake and diet fed during early- to mid-gestation influences post-natal DNA methylation of imprinted genes in muscle and liver tissues in beef cattle

Discovery of epigenetic modifications associated with feed efficiency or other economically important traits would increase our understanding of the molecular mechanisms underlying these traits. In combination with known genetic markers, this would provide opportunity to improve genomic selection accuracy in cattle breeding programs. It would also allow cattle to be managed to improve favorable gene expression. The objective of this study was to identify variation in DNA methylation between beef cattle of differential pre-natal nutrition and divergent genetic potential for residual feed intake (RFI). Purebred Angus offspring with the genetic potential for either high (HRFI) or low (LRFI) RFI were prenatally exposed to either a restricted maternal diet of 0.5 kg/d average daily gain (ADG) or a moderate maternal diet of 0.7 kg/d ADG from 30 to 150 d of gestation. We performed DNA methylation analysis of differentially methylated regions (DMR) of imprinted genes (Insulin-like growth factor 2 (IGF2) DMR2, IGF2/H19 imprinting control region (ICR) and IGF2 receptor (IGF2R) DMR2) using post-natal samples of longissimus dorsi (LD) muscle taken from male and female calves at birth and weaning, and of LD muscle, semimembranosus (SM) muscle, and liver samples collected from steers at slaughter (17 months of age). Interestingly, for all three DMR investigated in liver, LRFI steers had higher levels of methylation than HRFI steers. In LD muscle, IGF2/H19 ICR methylation differences for heifers at birth were due to pre-natal diet, while for steers at birth they were mostly the result of genetic potential for RFI with LRFI steers again having higher levels of methylation than HRFI steers. While results from repeated measures analysis of DNA methylation in steers grouped by RFI revealed few differences, in steers grouped by diet, we found higher methylation levels of IGF2 DMR2 and IGF2R DMR2 in LD muscle of restricted diet steers at weaning and slaughter than at birth, as well as increased methylation in LD muscle of restricted diet steers compared with moderate diet steers at weaning and/or slaughter. Our results suggest that differential pre-natal nutrition, and divergent genetic potential for RFI, induces tissue- and sex-specific alterations in post-natal IGF2 and IGF2R methylation patterns and that these patterns can vary with age in Angus beef cattle.     

Preliminary observations of genetic susceptibility of elk (Cervus elaphus nelsoni) to chronic wasting disease by experimental oral inoculation.

To compare the genetic susceptibility of elk (Cervus elaphus nelsoni) with various alleles of the PRNP gene, which encodes the normal cellular prion protein, to chronic wasting disease (CWD), eight 8-month-old elk calves of 3 genotypes (2 132MM, 2 132LM, and 4 132LL) were orally dosed with CWD-infected brain material from elk. During postinoculation (PI) month 23, both 132MM elk had lost appetite, developed clinical signs of weight loss and central nervous system (CNS) dysfunction, and were euthanized. Two other elk (both 132LM) developed similar clinical signs of disease and were euthanized during PI month 40. All 4 affected elk had microscopic lesions of spongiform encephalopathy (SE), and PrPres, the disease-associated form of the prion protein, was detected in their CNS and lymphoid tissues by use of immunohistochemical (IHC) and Western blot (WB) techniques. These findings indicate that elk with MM and LM at codon 132 are susceptible to orally inoculated CWD. All 4 LL elk are alive at PI year 4 and are clinically normal, which suggests that 132LL elk may have reduced susceptibility to oral infection with CWD-infected material or may have prolonged incubation time.     

非合格种蛋孵化的商品肉鸡生产性能

集约化商品肉鸡生产企业的目标是每只入舍母鸡能够生产出最大数量的可孵化种蛋和最多的高质量雏鸡。在适当的饲养管理条件下,一只母鸡产蛋可超过180个,鸡肉产量达到270kg。这些生产数据在鸡只之间存在着非常大的差距,其原因可追溯至种蛋的收集标准、储存条件和孵化条件。在坚持种蛋选择与分级的基础上进行常规性的饲养管理,生产企业获得最大收益的目标不难实现。     

Short‐term physiological role of thyroxine administration on plasma metabolites and growth performance of Sterlet sturgeon Acipenser ruthenus

Thyroid hormones (THs) play important roles in regulating growth, development and physiological functions in vertebrates. To study the role of short‐term effects of thyroxine (T4) on metabolism and growth in female Sterlet sturgeon, thirty fish with a weight of 707.97 ± 37.15 g were divided into six tanks. Fish were injected intraperitoneal with (a) coconut oil alone (control), (b) 1 mg T4 kg per BW in coconut oil (T₁) and (c) 10 mg T4 kg per BW in coconut oil (T₁₀). Blood samples were collected at 0, 4, 7, 14, 28 and 60 days for plasma biochemical analysis, and body length and mass were determined at day 60. Based on results, higher growth was indicated in T₁₀ group. The highest T4 levels were observed on day 4 in the T₁ and T₁₀ treatments and gradually declined during the trial. Plasma T3 levels were highest on days 4 and 7 in the T₁ and T₁₀ groups, respectively. Plasma triglyceride levels were significantly elevated on day 28 in the T₁ group and on day 60 in the T₁₀ group. Plasma glucose concentrations were significantly elevated on days 7 and 14 in T₁₀ group. Overall, the present results suggest that a single injection of T4 can improve growth via changes in the metabolic profile of Sterlet sturgeon.     

Herd-level prevalence of Mycobacterium avium subspecies paratuberculosis by bulk-tank milk PCR in Fars province (southern Iran) dairy herds

A cross-sectional study was conducted from March to August 2006 in dairy herds in Fars province, southern Iran to determine the herd-level prevalence of Mycobacterium avium subspecies paratuberculosis (MAP) infection. Bulk-tank milk samples were collected from 110 dairy herds in the 3 districts (Shiraz, Marvdasht and Sepidan) of the province. Among study populations, 12 herds (11%, 95%CI: 5-17%) were positive for MAP infection based on IS900 nested PCR. The prevalence of positive milk samples in the three districts of Fars province was different ranging from 8.6% to 23% which was not statistically significant (P=0.19). It is recommended to conduct further epidemiologic studies to determine cow-level prevalence and risk factors for infection, and to evaluate the economic consequences of the MAP infection in the region.     

Study of male effect on feeding and estrus behavior of Afshari ewes

Tropical Animal Health and Production - This study was conducted to evaluate the male effect on the manifestation of estrus and feeding behavior of Afshari ewes during their breeding season. The...     

Growth enhancement of rainbow trout (Oncorhynchus mykiss) by passive immunization against somatostatin-14

Juvenile rainbow trout (Oncorhynchus mykiss) were passively immunized by intraperitoneal immunization against somatostatin-14 (SS-14) using an antibody originating from egg-laying chicken (Gallus domesticus). Fish were immunized weekly (0, 7, 14, 21, 28, 35 days) with chicken egg yolk-derived immunoglobulin (IgY) against SS-14 (1:25 IgY, 5 mg mL^?1), and growth performance, feed utilization as well as plasma concentrations and mRNA levels of growth hormone (GH) and insulin-like growth factor I (IGF-I) were compared to the control group that received placebo immunization with PBS. Passive immunization significantly increased weight gain of treated fish (67.7 ± 7.4 g) compared to the control group (40.1 ± 2.0 g) after 35 days (p < 0.05). Feed conversion ratio (FCR) was significantly improved in the immunized fish (0.7 ± 0.08) compared to control group (1.2 ± 0.06) (p < 0.05). The concentrations of GH and IGF-I in the blood plasma showed no significant differences between the fish treated with anti-SS-14 and those of control during the treatment (p > 0.05). In both groups, GH levels decreased over the 35 days of the experiment (p < 0.05). However, IGF-I level during the period of treatment remained unchanged in both control and immunized fish with the anti-SS-14. Similarly, no changes were observed in pituitary GH and liver IGF-I mRNA levels between treatment and control at each sampling time (p > 0.05). There was no indication of a cumulative, long-lasting effect of repeated immunization on GH or IGF-I plasma concentrations or mRNA expression. The present study shows that a passive immunization of rainbow trout against SS-14 using a chicken egg yolk-derived SS-14 antibody could increase growth rate and improved FCR.     

Synthesis and characterization of nanocrystalline CoWO4@silk fibers with antibacterial activity under ultrasound irradiation

The present investigation reports the novel synthesis of CoWO₄ nanoparticles@silk fiber under ultrasound irradiation. The effect of temperature, power of ultrasound irradiation and sequential dipping steps in growth of the CoWO₄ particles were studied. Results show a decrease in the particles size as the temperature and power of irradiation decreased. The fibers containing CoWO₄ nanoparticles were tested for their antibacterial efficacy against E. coli and S. aureus and were found to possess significant antibacterial activity. The results show the CoWO₄ nanoparticles@silk with strongest fluorescence characteristics can be obtained in this method. The physicochemical properties of the nanoparticles were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectroscopy.