The Effect of Pasture Nitrate Concentration and Concentrate Intake after Turnout on Embryo Growth and Viability in the Lactating Dairy Cow

This study investigated the effects on embryo growth and survival rate of feeding heavily‐fertilised spring grass, containing high levels of quickly‐degradable nitrogen, to pregnant cows. Forty‐eight lactating Holstein cows between 2 and 8 weeks pregnant were turned‐out, after a one‐week transition period onto high‐ or low‐nitrate pasture and fed a high‐ or low‐concentrate supplement. Cows grazing the High nitrate pasture had significantly higher milk and plasma urea concentrations than cows grazing the Control pasture, while cows which were fed less concentrate had a notably higher plasma ammonia. However, there was no evidence that an increased quickly‐degradable nitrogen (QDN) intake from pasture affected embryo survival or growth from 20 days onwards. This suggests that the impact of turnout on fertility mainly affects ovulation, fertilisation and/or the early embryo.     

Variable nature of border disease on a single farm: clinical and pathological description of affected sheep

The clinical, pathological and virological findings in cases of Border disease occurring on a farm were studied. Fourteen abnormal lambs approximately three months old were obtained and were necropsied within 18 months at death or slaughter. Another lamb born during the study to a persistently infected ewe was also examined. The findings of these 15 animals are presented in three groupings. The animals of group A were persistently viraemic and hypomyelinogenesis was present in two lambs at one and 14 weeks old. Systemic, chronic, multifocal inflammation including nephritis, myocarditis and pneumonitis was found in older sheep. Group B lambs were non-viraemic and the predominant necropsy finding was cystic cerebral cavitation of variable severity. Histological examination showed cerebellar dysplasia and in two animals the retinas also showed multifocal photoreceptor cell atrophy. Lambs in group C were also non-viraemic and although these failed to thrive, no consistent pathological changes were found. It is concluded that the dams of animals in group A were infected in early pregnancy while those of animals in groups B and C were infected at mid-gestation or later.     

Determination of serum ionized calcium concentration in dairy cattle after frozen anaerobic storage

The stability of serum ionized calcium concentration (ICa) from dairy cows was studied after anaerobic collection and frozen storage. Paired blood samples were obtained from five groups of cows: nonlactating, first third of lactation, midlactation, last third of lactation, and 2-year-old nonlactating heifers. Vacutainer multiple sample needles and serum separator tubes (SST) were used for venipuncture. Aspiration of serum was within 1.5 hours after collection: one sample for immediate determination (within 2 hours of collection); the other sample stored at -4 degrees C in evacuated plastic vacutainer tubes filled with serum to provide dead space of less than 75% of volume, and analyzed after 14 to 30 days in storage (half, 15, of the samples from each lactation group were analyzed after frozen anaerobic storage at 14 or 30 days, respectively). Processing samples in this manner significantly altered the values obtained for ICa, normalized calcium concentration (NCa), and pH. Analysis after frozen storage in evacuated tubes caused ICa and NCa concentrations to decrease and pH to increase (P< 0.05); total calcium levels were not significantly different from initial values. There were no significant differences among lactation groups. The difference between values obtained from these paired samples was either due to loss of CO(2) during transfer from the SST to the evacuated tube or during frozen storage. Changes in samples assayed after freezing and storage could be adjusted to original values by using the mean difference between the fresh and frozen levels as correction factors: ICa (+0.4379), NCa (+0.2797), and pH (-0.0926). It was concluded that immediate determination of serum ICa in dairy cattle is the ideal but using this methodology and performing analyses later may be acceptable if correction factors are determined.     

关于加强对肉鸡非典型新城疫和低致病性禽流感防治的建议

随着对鸡传染病防制技术水平的提高和相应的高科技产品的推广运用,加上政府和广大养鸡场（户）对典型新城疫（ND）和高致病性禽流感（HPAIH5亚型）防制工作的重视,成功地控制了这两种疾病的发生。但当前肉鸡业最易忽视、危害又最大的却是非典型新城疫（CND）和低致病力H9亚型禽流感（LPAI）。所谓“重视”是大家都接种了AI和ND疫苗,而忽视的是对AI只接种H5亚型而未接种H9亚型禽流感疫苗;     

Comparison of efficiency of in vitro cloned sheep embryo production by conventional somatic cell nuclear transfer and handmade cloning technique

Conventional somatic cell nuclear transfer (SCNT) technique of in vitro production of cloned embryos involves use of costly and complicated micromanipulators. Handmade cloning (HMC) technique has been applied as efficient and cost‐effective alternative in many livestock species. The aim of the present study was to compare the efficiency of in vitro production and in vitro development of cloned sheep embryos by the two techniques. Cloned embryos were produced by conventional SCNT using micromanipulator apparatus and by HMC technique. Enucleation efficiency and efficiency of fusion with somatic cell (nucleus donor) were compared. Cleavage percentage was observed on day 2 of in vitro culture (IVC), and morula and blastocyst percentages were calculated on day 7 of IVC. Higher enucleation efficiency (96.98 ± 1.01 vs. 93.62 ± 1.03; p > .05) as well as fusion efficiency was obtained with HMC technique than with conventional SCNT (96.26 ± 1.34 vs. 92.63 ± 0.70, p < .05); 181 cloned sheep embryos were produced in vitro by conventional SCNT and 92 by HMC. Cleavage percentage observed on day 2 of in vitro culture was higher in HMC than SCNT (66.92 ± 3.72 vs. 55.97 ± 2.5, respectively, p < .05). Morula percentage obtained was higher in SCNT than HMC (44.12 ± 2.93 vs. 30.43 ± 6.79, respectively, p < .05), whereas blastocyst percentage obtained by HMC was higher (12.46 ± 4.96) than SCNT (5.31 ± 2.25; p > .05). It was inferred that HMC technique provides a cost‐effective and efficient method of in vitro production of cloned sheep embryos with a comparatively simpler technique with a possibility of automation. Efficiency of cloned embryo production could be improved further by propagating and standardizing this technique.     

Changes in plasma concentrations of S100A7 and S100A8 in dairy cows during pregnancy

This study was carried out to examine the changes in plasma concentrations of the Ca‐binding antimicrobial proteins S100A7 and S100A8 during pregnancy in dairy cows. Holstein Friesian cows (n = 19) were inseminated with Holstein Friesian semen. Blood was collected at days 30, 60, 90, 120, 150, 180, 210, 240 and 270 after insemination. Plasma was used for measuring the concentrations of S100A7 and S100A8. Both S100A7 and S100A8 concentrations showed similar patterns during gestation; they increased during the midgestation, between days 90 and 180, and then declined before calving. The findings indicated that plasma concentrations of S100A7 and S100A8 did not change significantly during pregnancy in cows. Further studies are required to determine the roles of S100A7 and S100A8 in physiological function during pregnancy in dairy cows.     

Resynchronising returns to service in anoestrous dairy cows in the South Island of New Zealand

AIMS: To investigate the effect of targeted resynchronisation of cows treated for non-observed oestrus before the planned start of mating (PSM), that were not detected in oestrus or pregnant 23 days after treatment (phantom cows), on the proportion pregnant at 42 days after PSM and the end of mating.

METHODS: Farm staff from eight herds in two regions of the South Island of New Zealand identified 1,819 cows not showing oestrus by 10 days before PSM. These cows were treated with intravaginal progesterone for 7 days, and I/M gonadorelin 10 days and 1 day before PSM. Three days before PSM they were injected with cloprostenol and equine chorionic gonadotrophin, with fixed time artificial insemination (FTAI) at PSM. By 23 days after PSM, 1,218 cows had not returned to oestrus. Of these, 161 cows confirmed not pregnant by transrectal ultrasonography were randomly assigned to no treatment (control group; n=74) or were resynchronised 25 days after PSM using the same treatment programme as above, with FTAI 35 days after PSM (n=87). All cows that returned to oestrus were artificially inseminated until 42 days after PSM, when natural mating was used. All cows were examined using transrectal ultrasonography 80 to 90 days after PSM to confirm conception dates.

RESULTS: Of the 1,819 anoestrous cows treated before PSM, 526 (29 (95% CI=23.1–34.0)%) had not been observed in oestrus by 23 days after PSM and had not conceived, so were diagnosed as phantoms cows. For resynchronised cows, 42/87 (48 (95% CI=37.8–58.8)%) were pregnant by 42 days after PSM compared to 21/74 (28 (95% CI=18.1–38.7)%) control cows (p=0.009). At the end of mating 58/87 (67 (95% CI=56.6–76.7)%) cows in the resynchronised group were pregnant and 46/74 (62 (95% CI=50.9–73.2)%) in the control group (p=0.554). The hazard of conception from 21 to 42 days after PSM was 1.9 (95% CI=1.07–3.12) times greater for resynchronised than control cows (p=0.026).

CONCLUSION: In cows not observed in oestrus and treated before PSM, resynchronisation increased the proportion pregnant by 42 days after PSM.

CLINICAL RELEVANCE: The benefit of resynchronisation depends on the number of anoestrous cows before PSM and the number of phantom cows after PSM. However at the herd-level it is likely that providing advice to reduce the known risk factors for cows not being observed in oestrus before the PSM may well be more cost effective than identifying and treating a sub-population of phantom cows.