The effect of an intramammary infection (IMI) at calving on the milk yield of heifers during their first 200 days in milk was estimated by comparing monozygotic twins, where one member had a naturally occurring IMI detected at the first milking after calving and the other twin did not. A heifer with a Streptococcus uberis IMI produced 200 kg (7%) less milk during the first 200 d of lactation compared with her uninfected twin, with significant differences evident throughout the 200-d period. Similar milk losses were recorded for heifers that developed clinical mastitis or remained subclinical. An elevated milk somatic cell count for infected heifers was apparent only for the first month, although the somatic cell count tended to remain high during the second and third months. Milk protein concentrations were greater in the Streptococcus uberis-infected twin over the 200-d period, whereas fat and lactose concentrations showed little change. An IMI caused by Streptococcus uberis was associated with a lower milk yield, whereas an IMI by CNS was not, despite CNS-infected twins having a higher SCC than their uninfected twin for the first 30 d of lactation.
Source: Pearson et al. – Journal of Dairy Science, 96, 158-164, 2013
Complete abstract: www.m²-magazine/org > 026-25.02.2013