Effect of pre-slaughter fasting time on carcass yield, blood parameters and meat quality in broilers

Objective The aim of this study was to evaluate the effect of pre-slaughter fasting time on carcass yield, meat quality, blood parameters and glucose metabolism in broilers. Methods Four hundred and fifty Arbor Acres (AA) broilers at 42 days of age were divided into 5 groups with 6 replicates in each group and 15 chickens as one replicate. Following this period, broilers from each group were distributed among five groups according to pre-slaughter fasting period as 4, 8, 12, 16, or 20 h. Results With increasing fasting time, the carcass yield (p0.10), while the increase of fasting time resulted in a linear decrease of the blood glucose (p = 0.021) and, more specifically, the glycogen content of the liver and leg muscles (p<0.001). With increasing fasting time, the aspartate transaminase (p<0.01), uric acid (p<0.01), and triglycerides (p<0.01) in serum linearly downregulated, while the alanine aminotransferase was linearly upregulated. Conclusion The results of this study show a significant influence of fasting time on carcass yield and meat quality in broilers. Moderate fasting (8 to 12 h) before slaughter can reduce the weight loss of broilers. Prolonged fasting (≥16 h) increased body weight loss, decreased slaughtering performance and fluctuating blood indexes of broilers

Effects of dietary copper on elemental balance, plasma minerals and serum biochemical parameters of growing-furring male mink (Mustela vison)

The objectives of this study were to study the effects of different levels of dietary copper on copper and zinc balance, plasma minerals and serum biochemical parameters of mink in the growing-furring periods. One hundred and five standard dark male mink were randomly assigned to seven groups with the following dietary treatments: basal diet with no supplemental Cu (Control); basal diet supplemented with either 6, 12, 24, 48, 96, or 192 mg/kg Cu from copper sulfate, respectively. The average daily gain (ADG) linearly (P = 0.0026, P = 0.0006) responded to increasing levels of Cu; maximal growth was seen in the Cu24 group. Feed efficiency tended to improve with the increase of dietary copper level (linear P = 0.0010, quad, P = 0.0011). Fecal copper, urinary copper, retention copper responded in a linear (P < 0.05) fashion with increasing level of Cu. The effect of level of Cu was linear (P < 0.001) for plasma Cu concentration. The serum glutamic-oxalacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) activities were increased linearly (P < 0.05) with dose of Cu, but serum total protein (TP) and albumin (ALB) concentrations decreased linearly (P < 0.05) as dietary copper levels increased. Effect of level of Cu was linear (P < 0.001) for serum ceruloplasmin (CER) concentration or Cu-Zn superoxide dismutase (Cu-Zn SOD) activity. Supplemental dose of Cu linearly decreased serum triglyceride (TG) (P = 0.011) and total cholesterol (TC) (P = 0.007). Our results indicated that the activity of Cu-dependent enzymes was enhanced by increasing dietary Cu concentration and that supplementation of Cu in the diet of mink could alter the plasma lipid profile and copper concentration. Keywords: Mink, Copper, Plasma minerals, Serum biochemical parameter

Effects of dietary methionine supplementation on growth performance of cubs, nutrient digestibility, nitrogen metabolism and serum biochemical indicators of female blue foxes (Alopex lagopus)

The objective of the present study was to investigate the effects of methionine (Met) supplementation on growth performance of cubs, nutrient digestibility, nitrogen metabolism and serum biochemical parameters of female blue foxes. One hundred primiparous female blue foxes that were similar in breeding date, pedigree, age, and weight were selected for the trial. The foxes were randomly assigned to four groups (n = 25 each group) and fed diets supplemented with Met at 2 (Met2), 4 (Met4), 6 (Met6) and 8 g/kg (Met8), respectively, for 40 days. Our data showed that body weights at 20 and 40 d were significantly higher in the Met4 group than in the Met2 group (P < 0.05). The Met4 group also had the highest apparent digestibility of dry matter and crude protein compared with either the Met2, Met6, or Met8 group (P < 0.05). The serum Met and isoleucine (Ile) concentrations were significantly higher in the Met4 group than in the Met6 or Met8 group (P < 0.05). In summary, these data indicate that supplementary Met improves growth performance of cubs likely due to increased crude protein and dry matter and increased nitrogen retention of female blue foxes. The optimal amount of Met supplementation is 10 g/kg basal diet

Dietary glutamine improves meat quality, skeletal muscle antioxidant capacity and glutamine metabolism in broilers under acute heat stress

This study investigated the effects of glutamine (Gln) on meat quality, skeletal muscle antioxidant capacity and Gln metabolism in heat-stressed broilers. Three hundred 42-day-old broilers were randomly divided into five groups: a control group (23 ± 1°C), which was fed basal diet, and four experimental groups (34 ± 1°C), supplemented with 0, 5, 10, and 20 g Gln/kg of basal diet. The experiment lasted for 24 h. Compared with the control group, acute heat stress caused a significant reduction (p < .05) in meat pH, water-holding capacity (WHC), gumminess and hardness, and a significant increase (p < .05) in cooking loss (CL) and lightness (L*) values. However, dietary Gln (20 g/kg) increased (p < .05) meat pH, WHC, gumminess and hardness, but decreased (p < .05) meat CL and L* values in the acute heat-stressed group. In breast and thigh muscles, the acute heat stress group exhibited significantly (p < .05) higher concentrations of malondialdehyde (MDA), but significantly (p < .05) lower levels of Gln, glutamate and glutaminase than the control group; dietary 20 g/kg Gln significantly decreased (p < .05) MDA concentrations, while it increased (p < .05) glutathione, glutathione peroxidas, T-AOC, Gln, glutamate, and glutaminase levels in acute heat-stressed groups. Gln could increase meat quality by improving antioxidative capacity and Gln metabolism in heat-stressed broilers

Effects of dry dietary protein on digestibility, nitrogen-balance and growth performance of young male mink

The experiment was to study the nutrient digestibility and metabolism performance of male minks, which were fed different protein level diets during growth period. Effects of protein quantity on growth and development of minks and feed conversion ratio (FCR) were also investigated. Sixty healthy male minks of 45 d were randomly allocated into six groups with ten replicates, which was one sable for each replicate. The minks in six groups were fed diets in which protein levels were 28, 30, 32, 34, 36 and 38%, respectively. The six groups were denoted as P28, P30, P32, P34, P36 and P38. After 2 wk, all minks were weighed, average daily gains (ADG) were calculated, and the digestibility values of nutrients were determined. The results indicated that digestibility of calcium, nitrogen of fence, nitrogen deposition, net protein utilization (NPU), and biological value of protein (BV) were similar (P > 0.05), however, nitrogen intake greatly varied among groups (P < 0.01). Compared with group P28, groups of P34, P36 and P38 showed significant difference (P < 0.01) in ADG and FCR. In conclusion, it was recommended that adding 34% protein to mink diet would optimize production parameters including ADG, digestibility of nutrition, and FCR, and negative result was observed when diet protein was lower than 28%

Effect of Prey Species and Prey Densities on the Performance of Adult Coenosia attenuata

Mass production of Coenosia attenuata Stein at low cost is very important for their use as a biological control agent. The present study reports the performance of C. attenuata adults when reared on Drosophila melanogaster Meigen or Bradysia impatiens (Johannsem). Different densities (6, 9, 15, 24 and 36 adults per predator) of D. melanogaster or (6, 12, 24, 36 and 48 adults per predator) of B. impatiens were used at 26 ± 1 °C, 14:10 (L:D) and 70 ± 5% RH. The results concluded that C. attenuata adults had higher fecundity, longer longevity and less wing damage when reared on B. impatiens adults compared to D. melanogaster adults. Additionally, C. attenuata adults demonstrated greater difficulty catching and carrying heavier D. melanogaster adults than lighter B. impatiens adults. In this case, 12 to 24 adults of B. impatiens daily per predator were considered optimal prey density in the mass rearing of adult C. attenuata