Efeito da climatização por pressão negativa e diferentes fases da gestação na bioquímica sérica em matrizes suínas híbridas

Abstract

This study aimed to evaluate the influence of pregnancy phase on sows‟ serum biochemical profile in a commercial herd, and ambient handling physiological effects using negative pressure from wind tunnels in order to relief heat stress in sows from 35 to 100 days of pregnancy in a commercial herd. The study was conducted at a farm covering full breeding cycles, housing 1,700 sows from hybrid commercial lineage (Large White X Landrace) located in Santa Vitória/MG, Brazil, where the average environment historical temperature registrations are about 31°C, from October through February. All sows received the same feed. Two experiments were carried out. On first, five mL of blood sample were obtained via jugular venipuncture from each sow, at three different moments: early pregnancy, between three to eight days after mating (t1); mid pregnancy, from 35 to 40 days (t2); and late pregnancy, from days 100 to 105 (t3). Samples were previously identified and shipped in isothermal box to the Veterinary Clinical Laboratory of the Federal University of Uberlândia. After samples centrifugation, the serum was harvested and processed in the automated biochemical analyzer ChemWell for obtaining values of total protein, albumin, globulins, blood urea nitrogen (BUN), creatinine, triglyceride, alkaline phosphatase, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma glutamiltransferase (GGT). Values of each biochemical parameter at the different gestation phases were compared using ANOVA in a completely randomized design. When comparing variables between collection moments, total proteins and globulins levels were higher at early pregnancy (t1) when compared to t2 and t3 (p < 0.05). Albumin, BUN, creatinine and albumin/globulin ratio values increased throughout pregnancy (t1>t2>t3) (p<0.05). The GGT enzyme and triglyceride levels showed higher concentrations in t3, which represents the late pregnancy stage, when compared to t1 and t2 (p<0.05). The lowest values for alkaline phosphatase activity were observed at early pregnancy (p<0.05) although similar concentrations were found at t2 and t3 (p<0,05). By other hand, the highest values for ALT activity were detected only at early pregnancy (p<0.05). The results for AST did not vary between collection moments (t1=t2=t3) (p>0.05). In conclusion, physiological particularities of pregnant sows at the three different gestation periods interfere on serum biochemical profile, which provides information on females‟ health. In addition, the biochemical profile can be correlated to the farm management. In the second experiment, sixty sows from 0 to 5th farrowing order, were selected and distributed into two groups of 30 females each. This way, both groups were housed in a wind tunnel negative pressure gestation barn until the 35th day of gestation, when the experiment was started. Then, 30 sows remained in this place, called air-conditioned barn (CL group), and the other 30 animals were transferred to another identical barn, however without the wind tunnel (NC group). The following physiological evaluations and blood collections were performed in the same sows when they were at 35 and 100 days of gestation: serum parameters of total thyroxine (tT4), total triiodothyronine (tT3), total protein, albumin, globulin and triglycerides, and measurements of average surface body temperature (TSM), rectal temperature (TR), air temperature (Tar) and relative air humidity, as well as the gradients (TR - TSM), (TR - Tar) (Tar). In NC group, the gradients (TR - TSR) were lower at the end of pregnancy (p < 0.05) as well as the gradients (TR - Tar), (TSM - Tar) and serum triglyceride reduction (p < 0.05). Therefore, negative pressure wind tunnel system enhanced the convective heat exchange of the sows, reduced the energy expenditure of pregnant sows at the end of gestation, and promoted the maintenance of homeothermia.