Effect of chromium supplementation on productive and reproductive performances and some metabolic parameters in late gestation and early lactation of dairy cows

The objective of this study was to determine the effect of supplemental chromium as chromium-L-methionine (Cr-Met) on productive and reproductive performances and some metabolic parameters in late gestation and early lactation of dairy cows. Sixty multiparous Holstein dairy cows according to prior lactation, parity, body mass (682±33 kg), and expected calving date were divided equally (30 cows/treatment) and were randomly allocated to one of the two groups. One group received basal diet without Cr (control group) and another group received Cr-Met supplement added at manufacturer's recommended level (8 mg of "Cr"/head per day) from 21 days before expected calving date until 21 days of lactation. Supplemental Cr tended to increase milk yield (P=0.08) while percentage of lactose and lactose yield increased (P<0.01). Chromium supplementation decreased serum nonesterified fatty acids concentration at 7 days prepartum and 21 days postpartum. Serum insulin concentration for cows receiving Cr was higher than the control group (P=0.05). Serum cortisol concentration decreased (P<0.05) in prepartum period in supplemented group. Chromium did not affect concentrations of metabolic parameters at calving. However, serum glucose concentration increased at 21 days postpartum in the supplemented group (P<0.05). Chromium supplementation increased neutrophil and neutrophil to lymphocyte ratio in prepartum period (P<0.05). Based on serum concentrations of progesterone, days to first ovulation tended (P=0.07) to occur earlier in the supplemented group. Furthermore, days to first service and days to first estrus of the supplemented group occurred earlier than the control group (P<0.05) but days open, services per conception and conception rates at first insemination did not differ between two groups (P>0.05). Percentage of cyclic cows at 36 days postpartum and estrous behavior before AI was higher in the supplemented group.

The effect of different levels of organic and inorganic chromium supplementation on production performance, carcass traits and some blood parameters of broiler chicken under heat stress condition

A total of 250 broilers in a completely randomized design selected to evaluate the effect of different levels of chromium (Cr) supplementation on performance, carcass traits and some blood parameters of heat-stressed broiler chicks. All birds were kept under heat stress temperature (33 ± 3°C) and divided into five treatments groups. Each treatment consisted of five pens with 10 birds in each pen. The basal diets were supplemented with 0 ppb (control), 800 ppb Cr-L-Met (T(1)), 1,200 ppb Cr-L-Met (T(2)) or 800 ppb CrCl(3) (T(3)), and 1,200 ppb CrCl(3) (T(4)). The feed intake and body mass were measured at 10, 21, and 42 days of age. Blood samples were collected from two birds in each replicates to determine biological and hematological values at 28 and 42 days of age. There were no significant difference in mass gain and feed conversion of broilers that received Cr supplementations compared with controls. The serum glucose concentration decreased in broilers received organic chromium methionine supplements compared with other treatments groups. Slight but not significant increases were observed in serum high-density lipoprotein (HDL) concentration of treated groups than controls while the mean serum HDL concentration was significantly higher in T(2) group compared with control group. Serum low-density lipoprotein level decreased in broiler received organic Cr supplements (p < 0.05).