Effect of Udder Health Status and Lactation Phase on the Characteristics of Sardinian Ewe Milk

Mammary involution and inflammation are known to negatively affect milk quality. A trial was carried out to elucidate the mechanism by which udder health status and lactational phase determine compositional modifications in ovine milk. A total of 60 individual milk samples was collected from a group of 20 pluriparous Sardinian ewes from mid to late lactation. Each sample was assessed for its chemical characteristics, quantitative distribution of casein fractions, lactodynamographic characteristics, and enzymatic activity. Udders were classed as healthy, doubtful, or infected on the basis of repeated somatic cell counts, and samples were grouped in 3 classes of days in milk. Results indicated that both udder inflammation and mammary involution can increase plasmin (PL) activity (15.6 vs. 18.4 U/mL in healthy vs. infected udders; 14.0 vs. 20.2 U/mL in phase 1 vs. 3), which is responsible for an evident protein breakdown in milk. Significant differences between groups were observed for several characteristics. With regard to udder heath status, casein index was lower in the infected vs. healthy udders (74.8 vs. 76.6%), and beta(tot)-casein showed a similar trend (43.9 vs. 46.6%). As a consequence of protein degradation, gamma-casein (5.78 vs. 2.82%) and proteolysis index (7.60 vs. 3.82) increased in the infected group with respect to the healthy group. Udder health status also affected milk technological traits. Udder inflammation resulted in longer clotting time (20.7 vs. 16.5 min for infected vs. healthy, respectively) and in poorer curd firmness (35.6 vs. 47.6 mm for infected vs. healthy, respectively). Frequency of samples reactive to rennet was 100, 93, and 67%, respectively, for healthy, doubtful, and infected groups. With regard to lactational phase, a decrease in alpha(s1)-casein (39.13 vs. 29.36%) and beta(1)-casein (23.41 vs. 19.36%) occurred during phase 1 vs. 3, whereas kappa + alpha(s2)-casein increased (12.30 vs. 21.56%, phase 1 vs. 3). Correlation coefficients confirmed the role of PL in protein degradation. It was concluded that PL activity was strongly affected by both lactational phase and udder health status and, in turn, could be an important agent enhancing milk quality detriment

Effect of somatic cell count and lactation stage on sheep milk quality

In order to evaluate the effects of mammary health status and lactation phase on the qualitative parameters of ovine<br />milk, 213 individual milk samples were repeatedly collected from 40 primiparous Sarda ewes on a monthly basis. Yield,<br />physico-chemical characteristics, casein fractions quantitative distribution, somatic cell count (SCC), cheese making properties<br />and plasmin-plasminogen activity were determined on each sample. Repeated individual milk SCC were used as a<br />marker of udder health status, allowing the definition of three classes: &ldquo;Healthy&rdquo; (H), &ldquo;Infected&rdquo; (I) or &ldquo;Doubtful&rdquo; (D).<br />Samples were grouped into 4 classes of days in milk (DIM). To evaluate the influence of mammary health status and<br />phase of lactation, a mixed model was performed using the ewe as random effect. Milk physico-chemical parameters were<br />influenced both by the udder health status and by lactation phase. In particular, the udder health status adversely affected<br />&alpha;s1 and &beta;1-casein fractions (P<0.01) and curd firmness (P<0.05). Samples reactive to rennet were 92.73%, 70.65%<br />and 64.60% in &ldquo;H&rdquo;, &ldquo;D&rdquo; and &ldquo;I,&rdquo; respectively. Lactation phase influenced the overall milk composition and technological<br />characteristics. Plasmin activity was higher in the &ldquo;I&rdquo; group than in the others (16.1 vs 11.8 and 11.2 U/ml; P<0.01) and<br />it significantly (P<0.01) increased during lactation. In conclusion, both mastitis and mammary involution are proven to<br />exert a detrimental effect on milk quality since they enhance its endogenous proteolytic activity

Meat from wild ungulates: ensuring quality and hygiene of an increasing resource

Wild ungulate populations are increasing in Europe and Italy, with a consequent increase in culling rates and availability of their meats. Objectives of this review were to evaluate the trends of availability of meat from wild ungulates in Italy, to review the present knowledge on nutritional properties, sensorial characteristics, and hygiene problems of wild ungulate meat and to examine the critical steps that influence their hygiene and quality. Wild ungulate meat in Italy derives mainly from wild boar, roe deer and red deer and its availability has been increasing in the last decade. Total consumption of wild ungulate meat is low (0.1-0.3 kg per capita/year), but in some regions rises to significant levels, especially for hunters&rsquo; families (1.0-4.0 kg per capita/year). Wild ungulate meats generally have a low fat content, although with a certain variability associated with gender, hunting season, age and physiological conditions, and a favourable fatty acid composition. In general, they are darker, less tender and characterised by a more intense and peculiar flavour than meats from domestic ruminants. However, these properties also show a great inter- and intra-specific variability. Risks for the consumer associated with contaminants (heavy metals, radionuclides, organochlorine pesticides and polychlorinated biphenyls) and zoonoses are considered to be low. Critical steps from shooting in the field to the final marketing should be considered to ensure hygiene and quality of meats. Future research should focus on the variability of hunting modes, accuracy of shooting, field dressing and carcass processing, in order to understand how these practices influence the final microbiological and sensorial quality of wild ungulate meats