Milk production and blood metabolites of dairy cattle as influenced by thermal-humidity index
Thapelo W. Kekana & Florence V. Nherera-Chokuda & Mukengela C. Muya1 & Kabelo M. Manyama &
Khoboso C. Lehloenya
Tropical Animal Health and Production
https://doi.org/10.1007/s11250-018-1513-y
Short Communication
Abstract: The effects of high thermal stress on serum protein metabolites, milk production of transition dairy cows in semi-arid areas in
South Africa were evaluated. Forty, ± 8 months pregnant, Jersey heifers (± 26 months) in zero grazing management were selected
during summer from two semi-arid communal areas. Summer thermal-humidity index (THI) of the areas were THI-1 (72–83:
extreme caution) and THI-2 (75–87: danger). Blood samples were collected (21 days pre-partum, and 21 and 75 days postpartum)
and analysed for serum protein metabolites. Milk yield was recorded daily and samples collected for milk fat, protein,
lactose and urea nitrogen analysis. Heifers in THI-2 had lower (P < 0.05) total serum proteins, albumin and blood urea nitrogen
than THI-1. Post-calving, cows in THI-1 had higher (P < 0.05) TP (73.4 vs 67.9 g/l) and BUN (4.61 vs 3.77 mmol/l) at 21 DIM,
and lower (P creatinine at 21 and 75 DIM than THI-2 group. Milk yield, fat and protein in THI-2 were all lower (P < 0.05) than
THI-1 21DIM. The results confirm that heat stress affects utilisation of nutrients in transition dairy cows.
Keywords: Blood proteins . Milk production . Smallholder dairy cows.
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