Alastair Macrae

The impact of dystocia on dairy calf health, welfare, performance and survival

Up to one-third of dairy calves are born after dystocia and this is a major cause of calf mortality. This study investigated the neonatal physiology, survival, health and subsequent growth of dairy calves following dystocia and is the first longitudinal study to analyse multiple effects and to look beyond the perinatal period. A total of 455 live born Holstein calves (N: No assistance, n=360; FN: Farmer assistance but normally presented calf, n=82; FM: Farmer assistance of malpresented calf, n=13) were followed from birth to first service (heifers) or until leaving the farm (bulls). Compared to N calves, FN and FM animals had higher salivary cortisol concentrations at day 1 (P<0.001) and FN calves had lower passive immune transfer (P=0.03). Dystocia had no biologically significant impact on rectal temperature throughout the first 4 days (P>0.05). During the first 60 days, FM calves had a higher proportion of days with non-routine health treatments (P<0.05) and, by the time of weaning, mortality in FN and FM heifers was higher than in N calves (2.8×; P<0.01). However, in surviving calves, growth to first service was not affected by dystocia category (P>0.05). Calves which survive dystocia experience lower passive immunity transfer, higher mortality and higher indicators of physiological stress. Such calves have poorer welfare in the neonatal period and possibly beyond. Strategies need to be implemented to improve the subsequent health and welfare of such calves and to lower the incidence of dystocia.

Comparison of rumination activity measured using rumination collars against direct visual observations and analysis of video recordings of dairy cows in commercial farm environments.

Automated systems for monitoring the behavior of cows have become increasingly important for management routines and for monitoring health and welfare. In the past few decades, various devices that record rumination have been developed. The aim of the present study was to compare rumination activity measured with a commercially available rumination collar (RC) against that obtained by direct visual observations and analysis of video recordings in commercial dairy cows. Rumination time from video recordings was recorded by a trained observer. To assess observer reliability, data were recorded twice, and the duration of recorded behaviors was very similar and highly correlated between these 2 measurements (mean=39±4 and 38±4 min/2 h). Measurements of rumination time obtained with RC when compared with analysis of video recordings and direct observations were variable: RC output was significantly positively related to observed rumination activity when dealing with animals housed indoors (trial 1 video recordings: slope=1.02, 95% CI=0.92-1.12), and the limits of agreement method (LoA) showed differences (in min per 2-h block) to be within -26.92 lower and 24.27 upper limits. Trial 1 direct observations: slope=1.08, 95% CI=0.62-1.55, and the LoA showed differences to be within -28.54 lower and 21.98 upper limits. Trial 2: slope=0.93, 95% CI=0.64-1.23, and the LoA showed differences to be within -32.56 lower and 19.84 upper limits. However, the results were poor when cows were outside grazing grass (trial 3: slope=0.57, 95% CI=0.13-1.02, and the LoA showed differences to be within wider limits -51.16 lower and 53.02 upper). Our results suggest that RC can determine rumination activity and are an alternative to visual observations when animals are housed indoors. However, they are not an alternative to direct observations with grazing animals on pasture and its use is not advisable until further research and validation are carried out.

Predisposing factors for involuntary culling in Holstein–Friesian dairy cows

The objective was to identify predisposing factors for increased risk of involuntary culling in adult Holstein-Friesian dairy cows. Data were sourced from Scotlands Rural College (SRUC) Dairy Research Centre. Between September 2003 and August 2010 175 cows were culled, a herd culling rate of 33.7%. The major reasons for involuntary culling were fertility (27.4%) and udder problems (26.9%). In the analysis, the culled cows were matched with their cohorts that survived to a later lactation. To identify predisposing factors, a binary logistic model was applied. Cows with higher than average body condition score (BCS) at last service were five times [Odds Ratio (OR) = 4.8] more likely to be culled due to infertility. Cows with low protein yield on day 60 ± 5 in lactation were ten times less likely (OR = 0.1) to be culled. In first lactation heifers, only BCS at last service increased the risk of involuntary culling due to infertility (OR = 13.0). A high milk yield acceleration was a significant (P = 0.04) factor in increasing the risk, five times (OR = 5.2) more, of culling cows due to udder problems. In conclusion, a high BCS at last service, high milk protein yield at around day 60 in lactation and acceleration of milk yield after calving exposed cows to a risk of being culled involuntarily. In practice, monitoring of traits that indicate metabolic imbalance could assist identifying cows at high risk of being culled and contribute to reducing the associated risk through a more effective timely decision.

Mortality, hepatopathy and liver copper concentrations in artificially reared Jersey calves before and after reductions in copper supplementation

High winter mortality (28 per cent) in female Jersey calves (<one month) characterised by mild hepatopathy and enteropathy was investigated. Liver copper (Cu) was very high in casualties, but also high in culled, newborn males (19.2 ± 1.54 and 12.0 ± 2.74 sd mmol/kg dry matter (DM) respectively). Serum glutamate dehydrogenase (GLDH) was >80 IU/l in healthy females aged 3–24 weeks, and correlated with serum aspartate transaminase (AST). Copper supplementation of total mixed rations during lactation was excessive (40–60 mg added Cu/kg DM) and reduced to 16–28 mg Cu/kg, but supplementation of milk replacer and creep feed (10 and 35 mg added Cu/kg DM, respectively) continued. The syndrome recurred two years later, and liver Cu remained high in casualties (13.6 ± 2.6) and culled cows (6.38 ± 2.38 mmol/kg DM) prompting withdrawal of all Cu supplements. Mortality remained low (6–9 per cent) thereafter. Three years after removal of all Cu supplements, six culled newborn were examined postmortem; five had normal liver Cu (4.5 ± 1.73), but a sixth had 11.65 mmol/kg DM. In live, healthy calves (1-6 months old) sampled at the same time, GLDH and AST increased with age to levels found five years earlier, indicating possible subclinical hepatopathy. Causative links between Cu supplementation, high calf mortality and hepatopathy are plausible, and reductions in Cu supplementation may prove beneficial in other dairy herds.

Molecular detection of Sarcocystis lutrae in the European badger (Meles meles) in Scotland

Neck samples from 54 badgers and 32 tongue samples of the same badgers (Meles meles), collected in the Lothians and Borders regions of Scotland, were tested using polymerase chain reactions (PCRs) directed against the 18S ribosomal DNA and the internal transcribed spacer (ITS1) region of protozoan parasites of the family Sarcocystidae. Positive results were obtained from 36/54 (67%) neck and 24/32 (75%) tongue samples using an 18S rDNA PCR. A 468 base pair consensus sequence that was generated from the 18S rDNA PCR amplicons (KX229728) showed 100% identity to Sarcocystis lutrae. The ITS1 PCR results revealed that 12/20 (60%) neck and 10/20 (50%) tongue samples were positive for Sarcocystidae DNA. A 1074 bp consensus sequence was generated from the ITS1 PCR amplicons (KX431307) and showed 100% identity to S. lutrae. Multiple sequence alignments and phylogenetic analysis support the finding that the rDNA found in badgers is identical to that of S. lutrae. This parasite has not been previously reported in badgers or in the UK. Sarcocystis lutrae has previously only been detected in tongue, skeletal muscle and diaphragm samples of the Eurasian otter (Lutra lutra) in Norway and potentially in the Arctic fox (Vulpes lagopus).

Vitamin D status predicts reproductive fitness in a wild sheep population

Vitamin D deficiency has been associated with the development of many human diseases, and with poor reproductive performance in laboratory rodents. We currently have no idea how natural selection directly acts on variation in vitamin D metabolism due to a total lack of studies in wild animals. Here, we measured serum 25 hydroxyvitamin D (25(OH)D) concentrations in female Soay sheep that were part of a long-term field study on St Kilda. We found that total 25(OH)D was strongly influenced by age, and that light coloured sheep had higher 25(OH)D3 (but not 25(OH)D2) concentrations than dark sheep. The coat colour polymorphism in Soay sheep is controlled by a single locus, suggesting vitamin D status is heritable in this population. We also observed a very strong relationship between total 25(OH)D concentrations in summer and a ewe’s fecundity the following spring. This resulted in a positive association between total 25(OH)D and the number of lambs produced that survived their first year of life, an important component of female reproductive fitness. Our study provides the first insight into naturally-occurring variation in vitamin D metabolites, and offers the first evidence that vitamin D status is both heritable and under natural selection in the wild.

Short communication: Survival, growth to weaning, and subsequent fertility of live-born dairy heifers after a difficult birth

The experience of a difficult birth (dystocia) is traumatic and has adverse effects on the newborn in various species. Despite affecting up to 1 in 3 births in dairy cattle, studies on calves have been mostly limited to the first day of life. The objective of this study was to investigate the effects of dystocia on the survival to calving, growth to weaning, and subsequent fertility as nulliparous animals. Historical data from live-born Holstein heifer calves born from cows with various birth difficulty scores (no assistance; moderate; high difficulty) were obtained from 2 herds (Edinburgh herd: n=1,237; Crichton Royal Farm herd: n=721). Each herd was analyzed separately for birth weights, weaning weights, growth rate to weaning, number of services to conception, and age at first calving using REML and generalized linear mixed model analyses. Survival analysis (Cox proportional hazards model) was used in the Edinburgh herd to analyze the subsequent survival of live-born heifers, whereas descriptive data are presented for the Crichton Royal Farm herd. A higher mortality risk to weaning and to first service was observed in the live-born heifers that experienced moderate difficulty at birth compared with heifers born naturally. Surviving dystocial heifers had similar growth-to-weaning and fertility performance as heifers born naturally in both herds. It could be that the performance of dystocial heifers that survived to weaning was not affected or that it was compensated for by farm management. This study highlights long-term effects of the early experience of a difficult birth and thereby stresses the importance of preventing dystocia not just from the point of view of the adult cow, but also from the perspective of the calf. This would also improve farm efficiency and calf welfare.

Serological survey of British sheep flocks for evidence of exposure to ovine pestiviruses

Ovine pestiviruses have the potential to reduce productivity in the British sheep flock. However, their prevalence and impact are currently poorly understood. This study aimed to estimate the exposure to pestiviruses in adult breeding ewe stock. Blood samples collected for metabolic profiling before lambing were tested using an ELISA that detected antibodies raised to both bovine viral diarrhoea virus and Border disease virus. A group of 15 animals were tested per flock. A total of 34 farms were tested, of which 13 had at least one seropositive animal. In those positive flocks between one and nine of the animals tested antibody-positive. Positive flocks were identified in all regions of Great Britain. This work suggests that exposure to ovine pestiviruses is widespread, and that it is timely to investigate flock-level prevalence and possible production impacts of endemic infection.

The value of trans-scrotal ultrasonography at bull breeding soundness evaluation (BBSE): The relationship between testicular parenchymal pixel intensity and semen quality

Bull breeding soundness evaluation (BBSE) is commonly undertaken to identify bulls that are potentially unfit for use as breeding sires. Various studies worldwide have found that approximately 20% of the bulls fail their routine prebreeding BBSE and are therefore considered subfertile. Multiple articles describe the use of testicular ultrasound as a noninvasive aid in the identification of specific testicular and epididymal lesions. Two previous studies have hypothesized a correlation between ultrasonographic testicular parenchymal pixel intensity (PI) and semen quality; however to date, no published studies have specifically examined this link. The aim of this study, therefore, was to assess the relationship between testicular parenchymal PI (measured using trans-scrotal ultrasonography) and semen quality (measured at BBSE), and the usefulness of testicular ultrasonography as an aid in predicting future fertility in bulls, in particular those that are deemed subfertile at the first examination. A total of 162 bulls from 35 farms in the South East of Scotland were submitted to routine BBSE and testicular ultrasonography between March and May 2014, and March and May 2015. Thirty-three animals failed their initial examination (BBSE1) due to poor semen quality, and were re-examined (BBSE2) 6 to 8 weeks later. Computer-aided image analysis and gross visual lesion scoring were performed on all ultrasonograms, and results were compared to semen quality at BBSE1 and BBSE2. The PI measurements were practical and repeatable in a field setting, and although the results of this study did not highlight any biological correlation between semen quality at BBSE1 or BBSE2 and testicular PI, it did identify that gross visual lesion scoring of testicular images is comparable to computer analysis of PI (P < 0.001) in identifying animals suffering from gross testicular fibrosis.

Survey of dry cow management on UK commercial dairy farms

Dry period management of the dairy cow focuses on maximising milk production during the subsequent lactation but may include procedures that negatively affect dry cow health and welfare. A survey of dairy farmers in the UK was conducted to investigate dry cow management procedures. The questionnaire was completed by 148 farmers. Most farms (84 per cent) kept dry cows in dynamic social groups. The median length of the dry period was 56 days, and 83 per cent of farms stopped milking abruptly, regardless of milk production level at dry-off. Twenty-seven per cent of cows from respondent farms produced more than 20 kg of milk per day at dry-off. The majority of farms (78 per cent) used antibiotic dry cow intramammary tubes at dry-off, in combination with internal or external teat sealants. Procedures that were commonly practised and potentially stressful for dry cows included abrupt cessation of milking of high yielding cows and frequent changes in diet and social environment.