Effect of milking frequency and genotype on udder morphology and milk quality

Abstract

The effects of once (X1) vs twice (X2) daily milking on milk yield, milk composition, somatic cell count (SCC), and udder morphology were studied in 30 dairy goats from three different breeds (10 Majorera 10 Tinerfeña and 10 Palmera) in middle lactation period. Each goat was milked X1 or X2 at 10 and 14 hours intervals (left or right mammary gland respectively), during 6 weeks. The udder morphology was evaluated (cisternal height, nipple height and distance between nipples). Milking frequency affected cisternal height, decreasing significantly in X1 and X2 in Majorera goats (4.10% vs 3.42%), Tinerfeña goats (11.82% vs 8.81%) and Palmera goats (6.96% vs 2.81%). The differences in morphological parameters were due to X1 animals had stored more milk after 24 hours than X2 goats after 14 hours. However, no significant differences were observed for nipple height and distance between nipples. X1 milk yield was lower than X2 by 8.73% in Majorera goats, 14.87% in Tinerfeña goats and 25.53% in Palmera goats. This wide variation in yield losses between the studied breeds under X1 management may be due to differences in level of production and individual udder morphological characteristics of each breed. Yields of fat, protein, lactose, total solids and solids non fat tended to be higher for X2 than for X1 in Majorera and Tinerfeña goats but significant differences were found only for Palmera breed. Milk somatic cell count did not differ between treatments (P= 0.182) which is important because it has become an important quality index in goat milk. In conclusion, milking frequency had effects on udder morphology without negative effects on milk quality.