Cheesemaking in highland pastures: Milk technological properties, cream, cheese and ricotta yields, milk nutrients recovery, and products composition.

Summer transhumance of dairy cows to high Alpine pastures is still practiced in many mountainous areas. It is important for many permanent dairy farms because the use of highland pastures increases milk production and high-priced typical local dairy products often boost farm income. As traditional cheese- and ricotta-making procedures in Alpine pastures are central to this dairy system, the objective of this study was to characterize the quality and efficiency of products and their relationships with the quality and availability of grass during the grazing season. The milk from 148 cows from 12 permanent farms reared on a temporary farm located in Alpine pastures was processed every 2wk during the summer (7 cheesemakings from late June to early September). During each processing, 11 dairy products (4 types of milk, 2 by-products, 3 fresh products, and 2 ripened cheeses) were sampled and analyzed. In addition, 8 samples of fresh forage from the pasture used by the cows were collected and analyzed. At the beginning of the pasture season the cows were at 233±90d in milk, 2.4±1.7 parities, and produced 23.6±5.7kg/d of milk. The milk yield decreased with the move from permanent to temporary farms and during the entire summer transhumance, but partly recovered after the cows returned to the permanent farms. Similar trends were observed for the daily yields of fat, protein, casein, lactose, and energy, as we found no large variations in the quality of the milk, with the exception of the first period of Alpine pasture. The somatic cell counts of milk increased during transhumance, but this resulted from a concentration of cells in a lower quantity of milk rather than an increase in the total number of cells ejected daily from the udder. We noted a quadratic trend in availability of forage (fresh and dry matter weight per hectare), with a maximum in late July. The quality of forage also varied during the summer with a worsening of chemical composition. The evening milk (before and after natural creaming), the whole morning milk, and the mixed vat milk had different chemical compositions, traditional coagulation properties, and curd-firming modeling parameters. These variations over the pasture season were similar to the residual variations with respect to chemical composition, and much lower with respect to coagulation and curd-firming traits. Much larger variations were noted in cream, cheese, and ricotta yields, as well as in nutrient recoveries in curd during the pasture season. The protein content of forage was correlated with some of the coagulation and curd-firming traits, the ether extract of forage was positively correlated with milk fat content and cheese yields, and fiber fractions of forage were unfavorably correlated with some of the chemical and technological traits. Traditional cheese- and ricotta-making procedures showed average cream, cheese, and ricotta yields of 6.3, 14.2, and 4.9%, respectively, and an overall recovery of almost 100% of milk fat, 88% of milk protein, and 60% of total milk solids.

The effect of the chamber on kinetic results in cryopreserved bull spermatozoa.

In this study, the effect of the chamber used for the automated analysis of sperm motility by a computer-assisted semen analysis system on sperm kinematics was evaluated, and the cause of this effect was also verified. Twenty-three bull semen batches were thawed, and semen was diluted, aliquoted and analysed with six different chambers, (three capillary-loaded chambers and three droplet (DR)-loaded chambers). For each chamber type, each sample was analysed in quadruplicate, and the reliability of the analysis was tested using an intraclass correlation coefficient (ICC). Furthermore, sperm membrane integrity (MI) was evaluated, for each sample and chamber, in 12 randomly selected central and 12 edge fields. The ICC analysis showed that some parameters could have a significant variability related to the chamber. High stability of results was detected in Leja 4-chamber slide. Furthermore, as previously reported in other studies, capillary-loaded chambers seemed to affect the total and progressive motility and sperm velocities (average path velocity, straight line velocity and curvilinear velocity). These findings were corroborated by the evaluation of sperm MI that was significantly higher in the DR-loaded chambers. This study confirms that the chamber used for the objective kinetic evaluation of bull-thawed spermatozoa significantly affects the result. These differences could be present also in other species, even if the specific effect on the sperm kinematics should be verified. The Makler chamber seemed to give reliable results with negligible effects on sperm kinematics.