ABSTRACT
BACKGROUND: Development of the cow-calf bond post-partum and passive immunity of calves from spring-calving beef × beef (B×B) and beef × dairy (B×D) cow genotypes was determined using primiparous and multiparous (Experiment 1), and primiparous and second-parity (Experiment 2) animals. In Experiment 1, calves either suckled colostrum naturally ('natural-suckling') (n = 126), or were fed colostrum, using an oesophageal-tube ('artificially-fed') (n = 26), from their dam within 1-h post-partum. In Experiment 2, all calves (n = 60) were artificially-fed colostrum from their dam. Prior to colostrum suckling/feeding, colostrum was sampled for IgG analysis. The cow-calf bond was assessed using CCTV recordings during the first 4-h post-partum. Calves were blood sampled at 48-h post-partum to determine IgG and total protein (TP) concentrations, and zinc sulphate turbidity (ZST) units. RESULTS: There was no difference (P > 0.05) in cow licking behaviours and calf standing and suckling behaviours between the genotypes, except in Experiment 2 where B×D calves had more attempts to suckle before suckling occurred (P ≤ 0.05) compared to B×B calves. In Experiment 1, multiparous cows licked their calves sooner (P ≤ 0.05) and for longer (P < 0.01), and their calves had fewer attempts to stand (P < 0.001), stood for longer (P = 0.05), and had fewer attempts to suckle before suckling occurred (P < 0.001) than primiparous cows; there was no parity effect on cow-calf behaviour in Experiment 2. Colostrum IgG concentrations and measures of calf passive immunity did not differ (P > 0.05) between the genotypes in either Experiment. In Experiment 1, colostrum IgG concentrations were greater (P ≤ 0.05) in multiparous compared to primiparous cows and their calves had superior (P ≤ 0.05) passive immunity; no effect of parity was found in Experiment 2. Passive immunity did not differ (P > 0.05) between suckled and artificially-fed calves in Experiment 1. CONCLUSIONS: Cow genotype had little effect on cow-calf behaviours, but under 'natural-suckling' conditions primiparous cows expressed maternal inexperience and their calves were less vigorous than multiparous cows. Colostrum IgG concentration and calf passive immunity measures were unaffected by genotype, but under 'natural-suckling' conditions calves from primiparous cows had lower passive immunity.
ABSTRACT
BACKGROUND: Summer scour syndrome (SSS) is a recently identified pathological condition affecting weaned dairy and dairy-beef calves during their first grazing season in Ireland. The syndrome is characterised by diarrhoea, weight loss, weakness, and can ultimately lead to death in some calves. Oral and oesophageal ulcerations are present in some cases. This study aimed to characterise a series of SSS cases in weaned dairy-bred calves on Irish commercial farms. RESULTS: Five farms with calves having unexplained diarrhoea at grass were referred by private veterinary practitioners (PVP) following preliminary testing to exclude coccidiosis and parasitic gastroenteritis. Farms were visited within 2 to 5 days following PVP's referrals, or 2 days to 3 weeks relative to the onset of clinical signs. Farm management data, grass and concentrate samples, and biological samples from 46 calves (8 to 10 calves/farm) displaying clinical signs were collected. Two farms were subsequently found positive for coccidiosis and/or had chronic pneumonia problems after a thorough herd investigation and were designated as non-case farms (NCF). The remaining three farms were deemed typical SSS outbreaks (case farms; CF). Mean rumen fluid pH per farm ranged from 6.67 to 7.09 on CF, and 6.43-6.88 on NCF. Mean rumen fluid ammonia concentrations ranged from 17.6 to 29.6 mg/L and 17.2-45.0 mg/L on CF and NCF, respectively. Corresponding blood ammonia concentrations ranged from 129 to 223 µmol/L and 22-25 µmol/L. Mean blood copper and molybdenum concentrations were within normal range on all farms. Grass crude protein concentrations on the paddocks where the calves had grazed, and were currently grazing on the day of visit ranged from 137 to 148 g/kg DM and 106-177 g/kg DM, respectively on CF, and 160-200 g/kg DM and 151-186 g/kg DM, respectively on NCF. On CF, inorganic nitrogen fertiliser was applied 1 to 3 weeks pre-grazing, whereas on the two NCF, inorganic nitrogen fertiliser was applied 2 to 3 weeks pre-grazing on one farm and no fertiliser was applied on the other. CONCLUSION: These findings suggest that copper or molybdenum toxicity, and ruminal acidosis are not the primary causes of SSS. High blood ammonia concentrations and the timing and level of inorganic nitrogen fertiliser application to paddocks pre-grazing, warrant further investigation.