Milk characteristics are affected by heat stress, but very little information is available on changes of milk protein fractions and their relationship with cheesemaking properties of milk. The main objective of the study was to evaluate the effect of hot season on milk protein fractions and cheesemaking properties of milk for Grana Padano cheese production. The study was carried out in a dairy farm with a cheese factory for transforming the milk to Grana Padano cheese. The study was carried out from June 2012 to May 2013. Temperature and relative humidity of the inside barn were recorded daily during the study period using 8 electronic data loggers programmed to record every 30 min. Constant managerial conditions were maintained during the experimental periods. During the experimental period, feed and diet characteristics, milk yield, and milk characteristics were recorded in summer (from June 29 to July 27, 2012), winter (from January 25 to March 8, 2013), and spring (from May 17 to May 31, 2013). Milk yield was recorded and individual milk samples were taken from 25 cows selected in each season during the p.m. milking. Content of fat, proteins, caseins (CN), lactose and somatic cell count (SCC), titratable acidity, and milk rennet coagulation properties were determined on fresh samples. Milk protein fraction concentrations were determined by the sodium dodecyl sulfate-PAGE. Data were tested for nonnormality by the Shapiro-Wilk test. In case of nonnormality, parameters were normalized by log or exponential transformation. The data were analyzed with repeated measures ANOVA using a mixed model procedure. For all the main milk components (fat, protein, total solids, and solids-not-fat), the lowest values were observed in the summer and the greatest values were observed in the winter. Casein fractions, with the exception of γ-CN, showed the lowest values in the summer and the greatest values in the winter. The content of IgG and serum albumin was greater in summer than in the winter and spring. A mild effect of season was observed for milk SCC, with greater values in summer than in the winter and spring. A worsening of milk coagulation properties was observed in summer season. The alteration of cheesemaking properties during hot season seems strictly linked with changes of milk protein fractions mainly with the decrease of αS-CN and β-CN and the increase of undefined proteins.

Heat shock proteins (Hsp) are known to protect cells from several stressors. Nucleotide changes in the flanking regions [5′-and 3′-untranslated region (UTR)] of Hsp gene might affect inducibility, degree of expression, or stability of Hsp70 mRNA. The present study aimed to investigate the association between inducible Hsp70.1 single nucleotide polymorphisms (SNPs) and heat shock (HS) response of peripheral blood mononuclear cells (PBMC) in dairy cows. Four hundred forty-six Italian Holstein cows were genotyped for four Hsp70

This study was undertaken to assess whether peripheral blood mononuclear cells (PBMC) isolated from Brown Swiss (Br) and Holstein (Ho) cows and stimulated with concanavalin A differ in response to chronic exposure to incubation temperatures simulating conditions of hyperthermia. Five multiparous Br and 5 Ho cows were utilized as blood donors. Peripheral blood mononuclear cells were subjected for 65 h to each of 5 treatments (T). Cells were exposed to 39 degrees C continuously (T39) and three 13-h cycles at 40 (T40), 41 (T41), 42 (T42) or 43 degrees C (T43), respectively, which were interspersed with two 13-h cycles at 39 degrees C. Treatment T39 was adopted to mimic normothermia; T40, T41, T42, and T43 mimicked conditions of more severe hyperthermia alternating with normothermia. Measures evaluated at the end of the incubation period were proliferative response (DNA synthesis), intracellular reactive oxygen species (ROS) concentrations, and mRNA abundance of the 72-kDa heat-shock protein (Hsp72). In Br cows, DNA synthesis began to decline when PBMC were repeatedly exposed to 41 degrees C (-22%), whereas DNA synthesis in cells isolated from Ho cows did not begin to decline until 42 degrees C (-40%). Furthermore, under T41 and T42, DNA synthesis from Br cows was lower than in Ho(-24 and -54%, respectively). In both breeds, increased incubation temperatures caused a reduction of intracellular ROS (from -39.6 and -69.7%). Increase in incubation temperatures enhanced Hsp72 mRNA levels only in PBMC isolated from Br cows. The Hsp72 mRNA in Br cows increased significantly under T41 and T43 compared with T39. In both breeds, DNA synthesis was positively and negatively correlated with intracellular ROS and Hsp72 mRNA abundance, respectively (r = 0.85 and r = -0.70, respectively). Results indicated that PBMC from Br cows are less tolerant to chronic heat exposure than those from Ho cows, and that the lower tolerance is associated with higher expression of Hsp72, suggesting that the same level of hyperthermia may be associated with a differential decline of immune function in the 2 breeds.

Heat stress (HS) induces adaptive responses that are responsible for alterations of carbohydrate and lipid metabolism. This study aimed to evaluate the effects of chronic heat treatment on the expression and secretion of leptin and adiponectin, important regulators of energy homeostasis, food intake and insulin action. C57BL/6 mice were subdivided into three groups (24 mice each). The first group was kept under control conditions (C: 22G2 8C). The second group was exposed to HS (35G1 8C). The third group was kept under control conditions and was food restricted (FR). The HS group had higher rectal temperature than the C and FR groups and lower food intake than the C group. Hspa1 (Hspa1a) gene expression in adipose tissue, muscle and liver was higher under HS than FR and C. Heat treatment resulted in decreased blood glucose and non-esterified fatty acids; increased leptin, adiponectin and insulin secretion; and greater glucose disposal. Leptin, adiponectin, leptin and adiponectin receptors, insulin receptor substrate-1 and glucose transporter mRNAs were up-regulated in HS mice. This study provides evidence that HS improves leptin and adiponectin signalling in adipose tissue, muscle and liver. Heat stress was responsible for improving insulin sensitivity and glucose uptake in peripheral tissues, probably mediated by adipokines. Changes in the adipokine levels and sensitivity to them may be considered as an adaptive response to heat.

Limited secretion of very low density lipoproteins (VLDL) in dairy cows is strongly related to fatty liver and other metabolic disorders in the early postpartum. Currently, there is limited information on which roles apolipoprotein B(100) (ApoB(100)), apolipoprotein E (ApoE), and microsomal triglyceride transfer protein (MTP) play in that VLDL limitation. To our knowledge, no studies have simultaneously measured ApoB(100), ApoE, and MTP mRNA in periparturient dairy cows. Therefore, a trial was conducted to assess liver gene expression of these proteins in transition dairy cows and to evaluate the relationships between their expression and metabolic status. Eight multiparous Holstein cows were monitored during the transition period. To evaluate metabolic and nutritional status, body condition score was registered, and plasma indexes of energy metabolism and VLDL were determined from 35 d before to 35 d after calving. Liver biopsies were performed on d -35, 3, and 35 relative to day of calving, and gene expression of ApoB(100), ApoE, and MTP were determined on liver tissue. Body condition, plasma glucose and VLDL decreased, and plasma NEFA and BHBA increased after calving. Compared with values of d -35, on d 3 after calving the ApoB(100) mRNA synthesis was lower, whereas MTP and ApoE mRNA abundance were higher. Negative correlation (r = -0.57) between plasma NEFA concentration and ApoB(100) mRNA abundance, and positive correlation between ApoB(100) mRNA abundance and plasma cholesterol (r = 0.65) and plasma albumins (r = 0.52) were detected at 3 d postpartum. Data on changes of gene expression of the 3 main proteins involved in the regulation of synthesis and secretion of VLDL in the liver suggest that decreased mRNA for ApoB(100) may be consistent with decreased synthesis and/or secretion of VLDL from liver during the periparturient period.