• Asian-Australasian Journal of Animal Sciences
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• 제23권2호
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• pp.205-212
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• 2010

The effects of chromium (Cr), dietary crude protein (CP) level, and potential interactions of these two factors were investigated in term of energy metabolism in lambs. Forty-eight 9-week-old weaned lambs (Dorper${\times}$Small-tail Han sheep, male, mean initial body weight = 22.96 kg${\pm}$2.60 kg) were used in a 2${\times}$3 factorial arrangement of supplemental Cr (0 ${\mu}g$/kg, 400 $\mu{g}$/kg or 800 ${\mu}g$/kg from chromium yeast) and protein levels (low protein: 157 g/d to 171 g/d for each animal, or high protein: 189 g/d to 209 g/d for each animal). Blood samples were collected at the beginning and end of the feeding trial. The lambs were then sacrificed and tissue samples were frozen for further analysis. Chromium at 400 ${\mu}g$/kg decreased fasting insulin level and the ratio of plasma insulin to glucagon, but these differences were not statistically significant; in contrast, chromium at 800 ${\mu}g$/kg increased the ratio significantly (p<0.05). Protein at the high level increased plasma tumor necrosis factor $\alpha$ (TNF-$\alpha$) level (p = 0.060). Liver glycogen content was increased significantly by Cr (p<0.05), which also increased liver glucose-6-phosphatase (G-6-Pase) and adipose hormone-sensitive lipase (HSL) activity. At 400 ${\mu}g$/kg, Cr increased muscle hexokinase (HK) activity. High protein significantly increased G-6-Pase activities in both the liver (p<0.05) and the kidney (p<0.05), but significantly decreased fatty acid synthase (FAS) activity in subcutaneous adipose tissue (p<0.05). For HSL activity in adipose tissue, a Cr${\times}$CP interaction (p<0.05) was observed. Overall, Cr improved energy metabolism, primarily by promoting the glycolytic rate and lipolytic processes, and these regulations were implemented mainly through the modulation by Cr of the insulin signal transduction system. High protein improved gluconeogenesis in both liver and kidney. The interaction of Cr${\times}$CP indicated that 400 $\mu{g}$/kg Cr could reduce energy consumption in situations where energy was being conserved, but could improve energy utilization when metabolic rate was increased.

• Asian-Australasian Journal of Animal Sciences
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• 제21권6호
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• pp.853-860
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• 2008

This experiment was conducted to study the effects of chromium (Cr), dietary crude protein (CP) level and potential interactions between these two factors on growth rate and carcass response, insulin activity and lipid metabolism in lambs. Forty-eight, 9-week-old weaned lambs (Dorper$\times$Small-tail Han sheep, mean initial body weight = $22.96kg{\pm}2.60kg$) were used in a $2{\times}3$ factorial arrangement of supplemental Cr (0 ppb, Cr0; 400 ppb, Cr1; or 800 ppb, Cr2 from chromium yeast) and CP levels (157 g/d to 171 g/d for each animal, LP; or 189 g/d to 209 g/d for each animal, HP). Growth data and blood samples were collected at the beginning and end of the feed trial, after which the lambs were killed. Both Cr additive groups and the HP group increased final weight and average daily gain, especially the Cr1 and HP group (p<0.01). HP increased pelvic fat weight (p<0.05), fat thickness of the 10th rib (p<0.05), longissimus muscle area (p<0.01) and rate of deposition of intramuscular fat (p<0.01). Supplemental Cr decreased the rate of deposition of intramuscular fat (p<0.05). Fasting insulin level and the ratio of insulin to glucose were lower with Cr1 than other groups, but with no significant difference. Glucose concentration was not affected by any treatment. Nonesterified fatty acids increased in the Cr1 (p<0.05) and HP (p<0.05) conditions and there was a significant $Cr{\times}CP$ interaction (p<0.05). Cr1 decreased triglycerides (p<0.05) and total cholesterol (p = 0.151) and HP increased high-density lipoprotein cholesterol (p<0.05). Cr1 decreased lipoprotein lipase activity in subcutaneous adipose tissue (aLPL, p<0.05) and the ratio of aLPL to lipoprotein lipase activity in skeletal muscle (mLPL, p = 0.079). mLPL and hepatic lipase (hHL) were not affected by any treatment. In the present study, Cr had limited effects on growth rate and carcass response, whereas Cr and CP had some notable effects on plasma metabolites and enzyme activities. Cr has a potential effect on energy modulation between lipid and muscle tissue. In addition, few $Cr{\times}CP$ interactions were observed.

• Asian-Australasian Journal of Animal Sciences
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• 제28권8호
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• pp.1140-1149
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• 2015

This research aimed to define the energy requirement of Dorper and Hu Hybrid $F_1$ ewes 20 to 50 kg of body weight, furthermore to study energy requirement changes with age and evaluate the effect of age on energy requirement parameters. In comparative slaughter trial, thirty animals were divided into three dry matter intake treatments (ad libitum, n = 18; low restricted, n = 6; high restricted, n = 6), and were all slaughtered as baseline, intermediate, and final slaughter groups, to calculate body chemical components and energy retained. In digestibility trial, twelve ewes were housed in individual metabolic cages and randomly assigned to three feeding treatments in accordance with the design of a comparative slaughter trial, to evaluate dietary energetic values at different feed intake levels. The combined data indicated that, with increasing age, the net energy requirement for maintenance ($NE_m$) decreased from $260.62{\pm}13.21$ to $250.61{\pm}11.79kJ/kg^{0.75}$ of shrunk body weight (SBW)/d, and metabolizable energy requirement for maintenance (MEm) decreased from $401.99{\pm}20.31$ to $371.23{\pm}17.47kJ/kg^{0.75}$ of SBW/d. Partial efficiency of ME utilization for maintenance ($k_m$, 0.65 vs 0.68) and growth ($k_g$, 0.42 vs 0.41) did not differ (p>0.05) due to age; At the similar condition of average daily gain, net energy requirements for growth ($NE_g$) and metabolizable energy requirements for growth ($ME_g$) for ewes during late fattening period were 23% and 25% greater than corresponding values of ewes during early fattening period. In conclusion, the effect of age upon energy requirement parameters in the present study were similar in tendency with previous recommendations, values of energy requirement for growth ($NE_g$ and $ME_g$) for Dorper and Hu crossbred female lambs ranged between the NRC (2007) recommendation for early and later maturating growing sheep.

• Asian-Australasian Journal of Animal Sciences
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• 제27권2호
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• pp.161-168
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• 2014

This study aimed to investigate dietary concentrate:forage ratios (C:F) and undegraded dietary protein (UDP) on nitrogen balance and urinary excretion of purine derivatives (PD) in lambs. Four Dorper${\times}$thin-tailed Han crossbred castrated lambs with $62.3{\pm}1.9$ kg body weight at 10 months of age were randomly assigned to four dietary treatments in a $2{\times}2$ factorial arrangement of two levels of C:F (40:60 and 60:40) and two levels of UDP (35% and 50% of CP), according to a complete $4{\times}4$ Latin-square design. Each experimental period lasted for 19 d. After a 7-d adaptation period, lambs were moved into individual metabolism crates for 12 d including 7 d of adaption and 5 d of metabolism trial. During the metabolism trial, total urine was collected for 24 h and spot urine samples were also collected at different times. Urinary PD was measured using a colorimetric method and creatinine was measured using an automated analyzer. Intake of dry matter (DM) (p<0.01) and organic matter (OM) (p<0.01) increased as the level of UDP decreased. Fecal N was not affected by dietary treatment (p>0.05) while urinary N increased as the level of UDP decreased (p<0.05), but decreased as dietary C:F increased (p<0.05). Nitrogen retention increased as dietary C:F increased (p<0.05). As dietary C:F increased, urinary excretion of PD increased (p<0.05), but was not affected by dietary UDP (p>0.05) or interaction between dietary treatments (p>0.05). Daily excretion of creatinine was not affected by dietary treatments (p<0.05), with an average value of $0.334{\times}0.005$ mmol/kg $BW^{0.75}$. A linear correlation was found between total PD excretion and PDC index ($R^2$ = 0.93). Concentrations of creatinine and PDC index in spot urine were unaffected by sampling time (p>0.05) and a good correlation was found between the PDC index (average value of three times) of spot urine and daily excretion of PD ($R^2$ = 0.88). These results suggest that for animals fed ad libitum, the PDC index in spot urine is effective to predict daily excretion of PD. In order to improve the accuracy of the spot sampling technique, an appropriate lag phase between the time of feeding and sampling should be determined so that the sampling time can coincide with the peak concentration of PD in the urine.

• Asian-Australasian Journal of Animal Sciences
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• 제26권10호
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• pp.1496-1503
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• 2013

The objective of this study was to determine the effect of municipal abattoir conditions and animal factors on avoidance-related behaviour (AB) of sheep at slaughter, bleeding times (BT) and mutton quality. The behaviour of 66 castrates and 19 ewes of different age categories was observed at three stages of slaughter. Higher behaviour scores indicated higher levels of AB. Time intervals between the start of blood flow and the time the flow changed from a constant stream into drips were recorded as BT. Thirty two meat samples were obtained to measure quality variables. These were colour ($L^*$, $a^*$ and $b^*$), $pH_{24}$, temperature, cooking loss (CL) and tenderness. Correlations were determined between BT and meat quality variables. Animal behaviour at slaughter differed with breed, gender and age group. Avoidance behaviour was higher in the Dorper breed than in both the Merino breed and their crosses. It was also higher in younger (<10 months) lambs than in older sheep. Castrates were more aggressive or in panic than ewes. Castrates had longer ($72.6{\pm}0.53s$) BT than the ewes ($63.6{\pm}2.82s$). Ewes had higher CL ($39.8{\pm}1.04%$) values than castrates ($35.1{\pm}0.95%$). Meat from castrates was tougher ($32.6{\pm}1.95N$) than the meat from ewes ($24.3{\pm}1.16N$). There were no significant correlations obtained between BT and meat quality variables. It can therefore be concluded that abattoir conditions, breed, age and gender had an effect on AB at slaughter. Gender had an effect on BT and mutton quality.