A new device to inseminate cows at the base of the uterine horns

A new device (Chapingo device) to deposit semen at the base of the uterine horns of cattle was developed at Universidad Autonoma Chapingo, Mexico. Nine Holstein heifers were inseminated by transvaginal laparoscopy, using a laparoscope for cattle and the Chapingo device. A dose of sexed semen (2.1 × 10⁶ spermatozoa) was deposited at the base of the uterine horn ipsilateral to the ovary where the preovulatory follicle was identified. Insemination was achieved in all the heifers, taking on average 13.7 ± 3.1 min per animal. In all cases, it was possible to see both ovaries, the base of the uterine horns and the oviducts. After the procedure, none of the heifers showed any type of complications such as haemorrhage, adhesions or trauma. On days 21 and 22 after insemination, four of the nine heifers (44.4%) returned into oestrus; on day 30 after insemination, one heifer was found to be pregnant by ultrasound. The results show the feasibility of generating pregnancies by transvaginal laparoscopy in heifers inseminated with sexed semen.     

Effects of meiotic inhibitors and gonadotrophins on porcine oocytes in vitro maturation,fertilization and development

This study evaluated the effect of three reversible meiotic inhibitors (MINs) and their interaction with gonadotrophins (Gns) on the meiotic maturation and developmental competence of porcine oocytes. In experiment 1, the oocytes were matured for 22 hr in the presence or absence of dbcAMP (1 mM), cycloheximide (7 μM) or cilostamide (20 μM) with or without Gns, and for an additional 22 hr in the absence of MINs and Gns. At 22 hr of maturation, regardless of the presence of Gns, a higher proportion (p < .001) of oocytes cultured in the presence of MINs were effectively arrested at the germinal vesicle stage compared with the oocytes cultured without MINs. At 44 hr of maturation, the proportion of oocytes that reached MII was higher (p < .05) in groups with Gns compared with groups without Gns. In experiment 2, oocytes that were matured as in experiment 1 were inseminated and cultured for 7 days to evaluate fertilization parameters and blastocyst formation. Only oocytes from the dbcAMP + Gns group had higher (p < .05) efficiency of fertilization compared with the other treatment groups. The presence of dbcAMP during maturation also increased (p < .05) blastocyst formation and efficiency of blastocyst formation in both the presence and absence of Gns. These results indicate that the interaction of Gns with the tested MINs improved meiotic progression. In addition, regardless of supplementation with Gns, the presence of dbcAMP during the first maturation period increased and even doubled the capacity of oocytes to develop to the blastocyst stage.     

Influence of Livestock Grazing and Climate on Pinyon Pine (Pinus edulis) Dynamics

Over the last century there has been marked expansion and infilling of pinyon (Pinus spp.)–juniper (Juniperus spp.) woodlands into grassland and shrubland ecosystems across the western United States. Although range expansions in pinyon-juniper populations have been documented with changing climate throughout the Holocene, over the last century, local scale impacts such as livestock grazing, changes in fire regimes, and increasing atmospheric CO₂ concentrations are thought to be more recent drivers of pinyon-juniper woodland distribution. Our objective was to examine the role of historical livestock grazing relative to past climate in regulating pinyon (Pinus edulis Engelm.) recruitment and growth over the last century in a persistent pinyon-juniper woodland. We compared pinyon dynamics on a remote mesa site, minimally grazed by domestic livestock, to a nearby historically grazed site in southeastern Utah. The presence of a significant number of old trees (> 200 yr) at both sites suggests that these populations were well established prior to the 20th century. No differences in pinyon density or basal area were observed between grazed and ungrazed sites. Stand age structure data showed that pinyon recruitment across these sites was highly synchronous, with a large recruitment event occurring during the early 1900s; 17% of the pinyons on both sites dated to the 1920s. Climatic conditions during this decade were consistently cool and wet—conditions known to support enhanced recruitment and growth in pinyon pines. Pinyon growth was also strongly synchronous across sites (r = 0.96). Pinyon growth was significantly correlated with winter/spring precipitation and negatively correlated with June temperature. Taken together, our results suggest that past climate may be more important in structuring pinyon populations than historical land use in these persistent pinyon-juniper woodlands. Given future climate projections of increasing temperature and more extended drought periods, regeneration of pinyon populations following the recent regional-scale dieback may be slow. Moreover, prolonged drought combined with potentially slow regeneration times for pinyon under future climate scenarios could result in substantial declines in pinyon populations across the region, a result that land managers should consider when planning for future restoration treatments in persistent pinyon-juniper woodlands.     

Pressure-induced amorphization and negative thermal expansion in ZrW2O8

It has recently been shown that zirconium tungstate (ZrW2O8) exhibits isotropic negative thermal expansion over its entire temperature range of stability. This rather unusual behavior makes this compound particularly suitable for testing model predictions of a connection between negative thermal expansion and pressure-induced amorphization. High-pressure x-ray diffraction and Raman scattering experiments showed that ZrW2O8 becomes progressively amorphous from 1.5 to 3.5 gigapascals. The amorphous phase was retained after pressure release, but the original crystalline phase returned after annealing at 923 kelvin. The results indicate a general trend between negative thermal expansion and pressure-induced amorphization in highly flexible framework structures.     

Relationships among Puberty,Muscle and Fat,and Liveweight Gain during Mating in Young Female Sheep

Greater depths of muscle are associated with better reproductive performance in ewe lambs, but, in adult ewes, reproductive performance also seems to vary with liveweight gain during the mating period. Therefore, in a large field study with Merino ewe lambs, we tested whether the relationships among eye muscle depth (EMD), fat depth (FAT) and reproductive performance depend on liveweight gain during the mating period. We selected lambs with a wide range in phenotypic values for depths of eye muscle (EMD) and fat (FAT) and assigned them to dietary treatments designed to achieve low (LOW, n = 244) or high (HIGH, n = 237) rates of liveweight gain during a 28‐day mating period. The LOW treatment maintained live weight, whereas the HIGH treatment gained 179 ± 3.8 g/day (p < 0.001). From those ewe lambs that attained puberty, first oestrus was detected at live weight 37.8 ± 0.2 kg and age 232 days. The proportion of ewes that attained puberty increased with EMD (p < 0.01). Ewes from the HIGH treatment were more fertile (pregnant ewes per 100 ewes exposed to rams) and had a higher reproductive rate (foetuses in utero per 100 ewes exposed to rams; p < 0.001) than those from the LOW treatment. Fertility and reproductive rate were positively correlated with weight gain during mating as well as live weight at the start of mating, FAT and EMD (p < 0.05 to <0.001). We conclude that faster growth, due to either extra nutrition during mating or higher phenotypic potential for fat and muscle, will increase reproductive performance in ewe lambs mated at 8 months of age.     

Practices and opinions of New Zealand beef cattle farmers towards bovine viral diarrhoea control in relation to real and perceived herd serological status

ABSTRACT

Aims: To investigate the seroprevalence of infection with bovine viral diarrhoea (BVD) virus among 75 beef herds and seroconversion in cattle during early pregnancy, and to determine the practices and opinions of farmers towards BVD control and their association with real and perceived herd serological status.

Methods: Blood samples were collected before mating in 75 beef herds across New Zealand from 15 unvaccinated heifers that had delivered their first calf that season. Serum samples were tested for BVD antibodies using ELISA individually, and after pooling samples for each farm. Animals that were antibody-negative were retested at either pregnancy diagnosis or weaning. Farmers were asked to complete a detailed survey about herd demographics, BVD testing and vaccination practices, and opinions towards national BVD control.

Results: Based on the pooled serum antibody ELISA results, there were 28/75 (37%) negative herds, 15/75 (20%) suspect herds, and 32/75 (43%) positive herds. Of 1,117 animals sampled 729 (65.3%) tested negative for BVD virus antibodies; when retested, 47/589 (8.0%) animals from 13/55 (24%) herds had seroconverted. Among 71 famers providing survey responses 11 (15%) believed their herd was infected with BVD, 24 (34%) were unsure and 36 (51%) did not think their herd was infected. Only 19/71 (18%) farmers had performed any BVD testing within the past 5 years and 50/70 (71%) had not vaccinated any cattle for BVD. Support for national BVD eradication programme was strong in 51/71 (56%) respondents, but the biggest challenge to BVD control was considered to be famer compliance. Compared to farmers who did not think their herd was infected, more farmers who thought BVD was present in their herds had previously tested for BVD, would consider testing all replacement calves, and would support establishing a national BVD database; fewer would consider purchasing BVD tested or vaccinated cattle only.

Conclusions and clinical relevance: Only 15% of the beef farmers in this study believed their herds were infected with BVD virus and few of them had undertaken BVD screening. Nevertheless many were supportive of implementing a national BVD control programme. It is likely that the lack of farmer awareness around BVD and the failure of farmers to recognise the potential impacts in their herds are hindering progress in controlling the disease in New Zealand. There are opportunities for New Zealand veterinarians to be more proactive in helping beef farmers explore BVD management options.     

小篷竹群落邻体干扰指数的研究

运用邻体干扰指数模型,分析小蓬竹群落种内、种间竞争强度,确立小蓬竹群落的竞争干扰因子。结果表明,在小蓬竹群落中,对小蓬竹干扰指数最大是猴樟,其次是小蓬竹本身。在自然情况下的群落演替过程中,猴樟种群将占优势,最终小蓬竹将在小蓬竹群落彻底消失。