Semen from 13 bulls, eight with clinical bovine spongiform encephalopathy (BsE), was used to artificially inseminate (AI) 167 cows with clinical BSE, and their resultant embryos were collected non‐surgically seven days after Al. The viable and non‐viable embryos with intact zonae pellucidae were washed 10 times (as recommended by the International Embryo Transfer Society) then frozen. Later, 587 of the viable embryos were transferred singly into 347 recipient heifers imported from New Zealand, and 266 live offspring were born of which 54.1 per cent had a BSE‐positive sire and a BSE‐positive dam. The recipients were monitored for clinical signs of BSE for seven years after the transfer, and the offspring were monitored for seven years after birth. Twenty‐seven of the recipients and 20 offspring died while being monitored but none showed signs of BSE. Their brains, and the brains of the recipients and offspring killed after seven years, were examined for BSE by histopathology, PrP immunohistochemistry, and by electron microscopy for scrapieassociated fibrils. They were all negative. In addition, 1020 non‐viable embryos were sonicated and injected intracerebrally into susceptible mice (20 embryos per mouse) which were monitored for up to 700 days, after which their brains were examined for spongiform lesions. They were all negative. It is concluded that embryos are unlikely to carry BSE infectivity even if they have been collected at the end‐stage of the disease, when the risk of maternal transmission is believed to be highest.

Pedigree beef cattle breeders who record with the Signet Beefbreeder service have their records analysed by a Best Linear Unbiased Prediction (BLUP). BLUP uses the records (weights and measurements) that have been recorded, for the individual and related animals, to determine the likely performance of an individual’s progeny. The analysis calculates Estimated Breeding Values (EBVs) for several traits of economic value, which are the assessments of genetic merit of the animal. EBVs are calculated for 200 day weight, 400 day weight, fat depth, muscle depth and muscle score. An economic assessment, or index, is calculated using this data, called the Beef Value. The objective of this experiment was to compare the performance of dairy-bred beef calves sired by bulls with either a high (top 10% of breed) or below average (bottom 25%) Beef Value.

Intensive cereal based rations for beef cattle are typically formulated to contain 175 g/kg DM crude protein. Many different sources of protein have been successfully used to supplement cereals. In this study, the performance of bulls fed three different protein supplements were compared, namely rapeseed meal (R), urea (U) and a combination of urea and soya (S). The study also examined the performance of beef cattle fed a yeast culture (Diamond V ‘XP’ Yeast - Rumenco).A total of 48 Limousin x (Hereford x Friesian) suckled bull calves at approximately 8 months old were allocated to one of three treatments with four replicates per treatment. Two replicates from each treatment were fed 40 g/head/day of yeast culture. Each diet was fed ad libitum with free access to barley straw and water. The feed ingredient inclusions in the rations were: R, 0.775 barley, 0.15 rape, 0.05 molasses, 0.025 minerals; U, 0.85 barley, 0.10 mineralised urea concentrate (Promol™ Rumenco), 0.05 molasses; S, 0.80 barley, 0.10 mineralised urea concentrate, 0.05 soya and 0.05 molasses. The R diet was used as the control. The bulls were slaughtered at fat class 4L. Statistical analysis was by ANOVA unless otherwise indicated.

Using a fluorescence technique which measures changes in oxygen concentration in embryo incubation medium, we have measured the uptake of oxygen by small groups of Day 7 bovine embryos recovered from superovulated and inseminated heifers (n = 8). The amount of glucose consumed by the embryos was also determined by analysing the spent medium following the oxygen assay. Oxygen consumption was successfully recorded from 17 out of 22 attempted assays and measured at 0.66 ± 0.08 nl embryo−1 h−1. There was a significant difference in oxygen consumption between blastocyst stage (0.84 ± 0.09) and expanded blastocyst stage (0.51 ± 0.09) embryos (P < 0.05). Mean ±(SEM) glucose uptake was 14.7 ± 1.9 pmol e−1 h−1 for all blastocysts; there was no significant difference in glucose consumption between blastocyst and expanded blastocyst stage embryos. From these values and assuming virtually all the glucose is metabolised via the Embden-Meyerhoff pathway, the rate of ATP production can be calculated at 205 ± 23 pmol e−1 h−1 (range 45–390 pmol e−1 h−1), of which approximately 85% is derived from oxidative phosphorylation. This rate represents a rapid turnover of ATP and demonstrates that metabolism in Day 7 bovine embryos is comparable to that of the more active tissues of the body.

Primiparous cows with low body condition at calving have an extended anovulatory period. Induction of ovulation and oestrus is possible with progesterone treatment but the response to this treatment differs between Friesian and Jersey breeds. The objective of this study was to describe changes in pulsatile LH secretion and the synchrony of developing ovarian follicles that occur during a progesterone treatment period of 5 days in primiparous anovulatory cows. The experimental model compared the progesterone treatment with spontaneous post-partum changes as well as a breed comparison in a factorial design.Thirty-six cows (Jersey n=19 and Friesian n=17) were managed to calve with a low body condition score (BCS<4.5). Daily changes in ovarian follicle size were observed with transrectal ultrasonography in each cow from 8 days post-partum. Thirty of these cows were diagnosed to be anovulatory at 12–18 days post-partum (day 0) and allocated to a treatment (n=16) or a control group (n=14), balanced for breed. Each treated cow had a progesterone-releasing controlled internal drug-releasing (CIDR) device inserted vaginally for 5 days while control cows were left untreated. Changes in plasma LH concentrations were measured with intensive blood sampling over 8 h on days −1, 1, and 4. Blood samples were also collected daily (06:00 h) for determination of plasma progesterone as well as oestradiol concentrations on days 6 and 8.Treatment with progesterone was associated with a transient initial decrease (day 1) in both LH pulse frequency and mean LH concentrations after device insertion, but both had returned to pre-treatment levels by day 4. Jersey cows had a greater pulse frequency, but there was no breed difference in mean LH concentrations. Patterns of ovarian follicle growth were affected by progesterone treatment with an increase in diameter of the dominant follicle (DF) identified after treatment initiation. This followed an earlier emergence of a new DF after device insertion. Follicular response to progesterone was dependent on the diameter of the DF present at treatment initiation. Those follicles ≥9 mm were replaced by a new DF during treatment such that the DF observed at the time of device removal was large (≥9 mm) and growing in 13/16 cases.Progesterone was not effective for the induction of an LH surge, ovulation and oestrus in anovulatory cows with a low BCS. However, treatment was associated with synchronous development of a DF so that it was large and growing at the end of the treatment period in most cases. This synchronous development may be due to the transient suppression of LH and the presence of an LH-dependent DF.