Milk and curd characteristics depending on farm and production level

Abstract

Here reported are data relative to the chemical composition/characteristics of the milk, of milk samples collected every 50 days from 60 buffaloes (326 samples) that were half-sibs (through paternal or maternal lineage, ascertained by DNA test), bred in two farms (S.A. and M respectively n. = 27 and n = 33). The subjects were divided in relation to the productive level (> vs. < 2601 kg/lactation). The production level did not influence the theoretical yield (ThCY), the yield at 4 h (FCY) and at 28 h (28CY), the curd dry matter (CDM) and the ratios between ThCY and real yields (FCY, 28CY and CDM). Compared to the less productive subjects, despite similar percentage of proteins, the more productive subjects had a higher percentage of casein (3.73 vs. 3.64; P < 0.05), a greater incidence of the latter on total protein (80.52 vs. 79.60; P < 0.05), higher content in lactose (4.88 vs. 4.81; P < 0.01) and urea (42.44 vs. 40.48; P < 0.05) and a lower BCS value (6.79 vs. 7.25; P < 0.05). These differences are not always confirmed in both farms. Regardless of the production level, subjects of farm S.A. had a lower production/lactation (2524 vs. 2817 kg; P < 0.01), higher values of R and k20 (P < 0.01), lower value of a30, a higher SH value and lower contents in urea and solid not fat. They also showed a lower ThCY yield and a lower ratio between ThCY and 28CY when proteins were corrected for the urea content, and a higher ratio between 28CY and the percentage of proteins, both when corrected or not for the urea content. It is difficult to explain the influence of the production level on the casein content whereas the greater lactose content in more productive buffaloes may be accounted for by the greater persistence of lactation curve. The higher urea content found in buffaloes with a greater galactopoietic attitude may be due to a greater DM intake caused by the inadequacy of the diet, hypothesis confirmed by the lower BCS observed in the more productive subjects.