No abstract

The aim of this study was to evaluate the heat tolerance of Bama miniature pigs under high ambient temperature (40°C) and Zn interactive functions during heat treatment (HT). Bama miniature pigs (male; n = 24; 6-mo old; BW = 10.79 ± 0.06 kg) were randomly allotted to 4 groups and were fed a basal diet or the basal diet supplemented with 1,500 mg of Zn (ZnSO4·H2O)/kg diet for 38 d. At 7 mo of age (d 30), the thermal neutral (TN) groups remained at 25°C, whereas the HT groups were exposed to ambient temperature at 40°C for 5 h daily for 8 consecutive days. Pigs in 4 groups were sacrificed on d 38. Individual rectal temperatures, skin temperatures, and breathing rates were recorded at 3 h after the onset of HT and the blood samples were collected immediately after HT on d 30, 34, and 38. Pigs fed diets with or without Zn doubled their breathing rates (P < 0.05) and increased body surface, scrotal, and rectal temperatures during HT on d 30, 34, and 38, respectively. Zinc supplementation increased BW gain (BWG; P < 0.05) during 38-d experiment period, and HT decreased BWG only from d 30 to 34 (P < 0.05). Heat treatment increased serum testosterone on d 30 (P < 0.05). Zinc supplementation decreased the heat-induced increase of testosterone in HT on d 30 and 34 (P < 0.05). The relative weight of liver increased in HT groups (P < 0.05). Zinc supplementation decreased the relative weights of spleen (P < 0.05) and testis (P < 0.01). The values of abnormal lymphocyte count and large unstained cell count declined approximately 5 times in groups of Zn supplementation, whereas Zn supplementation increased the values of red blood cell count, hemoglobin, hematocrit, mean corpuscular volume, and mean corpuscular hemoglobin. Zinc concentrations increased in serum, liver, kidney, epididymis, longissimus, hair, and feces in groups fed with Zn (P < 0.01). However, additional Zn decreased Zn concentrations in lung, spleen, and testis (P < 0.01). Moreover, HT decreased serum Zn concentrations (P < 0.01). In conclusion, Zn supplementation could be used to alleviate the decline of serum Zn during periods of high ambient temperatures. However, pretreated supplementation with pharmacological Zn did not promote heat tolerance but impacted the erythropoiesis, immunity, and reproductive organ development in Bama miniature pigs.

In order to investigate the effect of organic trace minerals premix (OTM) on the reproductive performance of breeder roosters, a total of 240 San Huang roosters (23 weeks of age) were randomly divided into two treatments with six replicates of 20 roosters each. The first group (n = 120) was fed a basal diet containing an inorganic trace minerals premix (ITM) and the other group (n = 120) was fed the basal diet in which ITM was replaced by OTM. The experiment period was 22 weeks. Semen from one randomly-selected rooster per replicate was collected two weeks after the beginning of the experiment and other 10 times every two weeks. Another rooster per replicate was randomly selected at 30, 35, and 45 weeks of age, and sacrificed. Results showed that OTM did not affect relative organ weights. There was a significant increase in semen parameters in OTM group (p<0.05), such as semen volume, semen density, and semen motility from 31 to 35 weeks. OTMfed roosters presented higher serum testosterone levels at 45 weeks of age, as well as higher testicular mRNA expression of the genes 3-beta dehydrogenase 2 (HSD3B2) and cytochrome P450 17A1 (CYP17A1) in the OTM-fed group at 45 weeks of age compared with those fed ITM (p<0.05). Considering the results of the present study, it was concluded that feeding organic instead of inorganic trace minerals to male broilers breeders improves semen quality, which may be attributed to their better testicular development and higher expression of enzymes related to testosterone synthesis.