ALBERT

Description: A shortage of nutrients during the final period of gestation can decrease secretion of colostrum, which is critical to newborn calf survival. The physiological mechanism modulating the nutritional control of colostrum secretion is poorly understood. Because the decline in progesterone before parturition is required for lactogenesis to occur, the objective was to evaluate the correlation between prepartum progesterone in cows and plasma immunoglobulin-G1 (IgG1) concentration in neonatal calves. From 135 pregnant cows, successful data on both prepartum progesterone and calf IgG1 was collected from 59 cow/calf pairs (animal ethics approval SA2018/05/638). The cow/calf pairs were classified into three categories according to the transfer of passive immunity: low (n = 19), medium (n = 18), or high (n = 22). Plasma IgG1 was 1025, 2395, and 3347 mg/dL for the low, medium, and high groups, respectively. Plasma progesterone 1 day prepartum was 18.3, 14.2, and 12.4 nmol/L for the low, medium and high groups, respectively. This indicates that calves with failure of passive transfer were born from cows with higher prepartum progesterone, compared to calves with high IgG1 (P = 0.05). Non-linear modelling of the progesterone data indicated the moment that progesterone started to decline (change-point). Change-point was 0.8, 2.5, and 2.4 days before parturition for the low, medium, and high groups, respectively. There was a delay in progesterone decline in the Low group compared with the High group (P 〈 0.05). These results corroborate the hypothesis that the delay in progesterone decline before parturition is responsible for the failure of IgG1 transfer from cows to calves.

Description: The net cost of calf loss between confirmed pregnancy and weaning in a north Australian beef business is 〉$400. [...]

Description: Across beef breeding herds of northern Australia, poor pre-partum nutrition of cows is consistently associated with increased calf wastage between confirmed pregnancy and weaning. With key nutrients at play (especially energy, protein, phosphorus and water) also being associated with milk yields, a specific problem mediating calf mortality is likely to be low milk production and delivery during the highest-mortality-risk period that is the first week after birth. Recent research demonstrated that milk-deprived newborn calves die of dehydration within 1–3 days. Newborn Brahman and tropical composite calves across three grazing herds (n = 75) and two penned herds (n = 106) were investigated. Calf milk uptake during the first 1–2 days of life was measured by plasma immunoglobulin (IgG) levels and overall milk uptake and health during the first two weeks of life was measured by growth rate from birth. Grazing calves with average IgG levels of 2247, 2508, and 2656 mg/100 mL had respective average growth rates of 0.5, 1.0, and 1.4 kg/d. Penned calves with average IgG levels of 2064, 2498 and 2504 mg/100 mL had respective average growth rates of 0.6, 1.0, and 1.4 kg/d. The association between calf immunoglobulin uptake and initial growth demonstrates individual variation between tropical beef calves for early milk uptake and that risk factors limiting milk delivery in the first days of life would place calves at greater risk of poor health and mortality.