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SUPPLEMENTAL DIETARY METHIONINE AFFECTS THE PELT QUALITY AND NUTRIENT METABOLISM OF RACCOON DOGS (NYCTEREUTES PROCYONOIDES)
LIU Hanlu, LI Guangyu, ZHONG Wei, LI Danli, LIU Fenghua , SUN Weill
Institute of Special Wild Economic Animal and Plant Science, CAAS, Jilin, China, [email protected]
Introduction: The Ussuriensis raccoon dog (Nyctereutes procy-onoides ussuriensis), also known as the one of raccoon dog, has unique pelt characteristics. Recently, raccoon dogs have been raised in captivity in China for the economic value of its pelt, and their numbers have increased rapidly. To date, the population of farmed raccoon dogs has reached about 13 million in China, mainly in the northeast and eastern coast area. It has been shown that methionine is the most important essential amino acid for mink and fox (Dahlman et al., 2002). Either insufficient or too much sulfur-containing amino acids in the diet of these animals could lead to certain functional disorders (Takahashi et al., 1991). This study was aimed to evaluate the effect of protein-reduced diet with variable amounts of supplemental methionine on the nutrient metabolism and pelt quality of raccoon dog.
Materials and Methods: All animal procedures were approved by The Wild Animal and Plant Subcommittee of the China Association of Agriculture Science Societies (WAPS CAASS), and all experiments were performed according to the animal health and well-being regulations.
Animal Care and Management: Seventy-five, 4-month old male raccoon dogs of similar body weight (5.13 ± 0.25 kg) were randomly assigned to five dietary treatments as described above. The experimental period encompassed the winter-fur-growing season, from the end of September to the end of November, 2008, a total of 60 days.
Experimental design and rations: In accordance with the Nutrition Requirements of Mink and Foxes (1982), the basic protein level in the experimental diets was 20% crude protein with supplemented methionine 0.15%, 0.355, 0.55% and 0.75% and lysine level of 0.65 g/100 g dry matter (DM).The complete diet components are shown in Table 1. One part diet powder was mixed with three parts water.
Table 1
Composition (%) of experimental basal diets (dry matter) and analysis of nutrient content of diets
Ingredient (%) Control Experimental groups receiving supplemental methionine (g/100 g DM)
Group 1 Group 2 Group 3 Group 4
Extruded corn 37.750 47.440 47.440 47.440 47.440
Soybean Meal 5.500 4.750 4.750 4.750 4.750
Meat and bone meal 12.000 7.000 7.000 7.000 7.000
Distillers dried grains with soluble 9.500 9.500 9.500 9.500 9.500
Corn gluten feed 15.000 16.500 16.500 16.500 16.500
Fish meal 13.500 6.500 6.500 6.500 6.500
Chicken oil 4.650 6.010 6.010 6.010 6.010
Lysine 0.450 0.650 0.650 0.650 0.650
Methionine (added) 0.150 0.150 0.350 0.550 0.750
Additives 1 1.000 1.000 1.000 1.000 1.000
Salt 0.500 0.500 0.500 0.500 0.500
Total 100.000 4098.000 100.000 100.000 100.000
Nutrient requirements of raccoon dogs in winter during the fur-production period3
Metabolizable energy ME (MJ/kg) 13.96
Crude protein CP, g/100 g DM 24.58
Crude fat Cfat, g/100 g DM 9.29
Calcium Ca, g/100 g DM 1.00
Phosphor P, g/100 g DM 0.72
Lysine Lys, g/100g DM 2 1.60
Methionine Met, g/100g DM 2 0.91
Sample Collection and Handling The raccoon dogs were weighed on days 30 and 58 after the start of experimental feeding, and the average weight was calculated. The total feces for 3 days were collected as a measure of the apparent macronutrient digestibility on day 45 of the experiment. Feed and fecal samples were dried at 65°C for 48 hours, ground in a mill to pass a 2-mm screen, and analyzed. Blood samples from raccoon dogs fasted for 12 hours were collected via hind leg puncture after 40 days and refrigerated overnight. After centrifugation for 20 minutes at 5000 xg, serum was collected and frozen at -20°C for later analysis. At the end of the experiment, all raccoon dogs were sacrificed and the pelts were collected 30 min later for evaluation of pelt properties.
Chemical Analysis Feed and fecal samples were analyzed for DM, crude protein, and crude fat using methods of the Association of Official Analytical Chemists (AOAC, 1990).
Pelt Properties Pelt weight and the length from the nose tip to the tail base were measured. The length of guard hair and under hair was also recorded. Hair density was counted under a microscope on a vertical section of skin with a net micrometer. The degree of under hair regularity was defined as the average length of under hair at the neck, dorsocentral, and lumbosacral regions.
Statistical Analysis For multiple comparisons, the one-way analysis of variance (ANOVA) was performed, and the differences between the means were compared using Duncan's multiple-range test and SAS 8.2 (SAS, Cary, NC) software. Treatment effects were considered significant at P < 0.05 and trends were observed at P < 0.10, unless otherwise noted.
Results Body Weight, Dry Matter Intake (DMI) and Apparent Nutrient Digestibility
At the end of the experiment, the body weight of the controls and groups 1, 2, 3 remained at similar levels, while the body weight of group 4 decreased
significantly compared to the control (P < 0.05; Table 2). According to the results, apparent nutrient digestibility was not affected by either a high protein diet mixed with low methionine, or a low protein diet mixed with high methionine.
Blood parameters Table 3 shows the effect of different levels of methionine on blood parameters. The methionine concentration in serum remained at a similar level among all groups, but the concentration of lysine increased considerably in group 4 when compared with the control (P < 0.05) and other groups (P < 0.05).
Effect of methionine level on body weight, DMI, DMD,
dogs (mean ± SD)
CPD
Table 2 CFD of raccoon
Items Control Group 1 Group 2 Group 3 Group 4
Body weight, kg 7.57±0.93a 7.02±0.87ab 7.26±0.82ab 6.79±0.96ab 6.90±0.88b
DMI, kg/d 0.34±0.03a 0.28±0.07bc 0.26±0.12bc 0.32±0.06ab 0.28±0.05abc
DMD, % DM 0.68±0.04a 0.73±0.04a 0.77±0.0.14a 0.75±0.06a 0.75±0.05a
CPD, % DM 0.67±0.05a 0.69±0.06a 0.73±0.16a 0.67±0.08a 0.68±0.07a
CFD, %DM 0.77±0.05a 0.80±0.11a 0.69±0.10a 0.74±0.06a 0.78±0.05a
Note: DMI, dry matter; DMD, dry matter digestibility; CPD, crude protein digestibility; CFD, crude fat digestibility; a ^ c In the same row, values with same superscripts mean no significant difference (P>0.05); with different letter superscripts mean significant difference (P<0.05).
Pelt Properties The body length and pelt weight was similar in all groups (Table 4). These results indicated that in the fur-growing period for raccoon dogs the diet of group 2, which contained 0.35 g methionine /100g DM (total 0.7 g methionine/100 g DM), improved pelt quality.
Conclusion In this study, we found that the diet containing 20 g protein + 0.7 g methionine /100 g DM gave raccoon dogs a better performance and higher pelt quality.
Table 3
Effect of methionine level on the serum index
Item Control Group 1 Group 2 Group 3 Group 4
Total protein, g/dl 7.65±1.28a 9.94±1.42ab 10.48±0.82b 8.88±0.84ab 9.00±1.17ab
Serum albumin, g/l 39.38±7.25a 35.65±5.64a 37.86±9.54a 42.64±5.77a 45.29±9.36a
Urea nitrogen, mg/l 5.50±0.48ab 5.39±0.96ab 4.64±1.16a 5.75±1.14b 5.80±1.04b
Methionine, mg/l 0.27±0.05a 0.28±0.04a 0.26±0.03a 0.27±0.05a 0.32±0.07a
Lysine, mg/l 0.80±0.14a 0.79±0.15a 0.77±0.09ab 0.86±0.02a 0.64±0.09c
Table 4
Effect of methionine level on pelt properties
Item Control Group 1 Group 2 Group 3 Group 4
Body length, cm 65.57±2.59ab 64.57±3.32ab 60.77±2.59ab 64.78±3.12ab 67.14±2.77a
Pelt length, cm 94.43±3.72a 93.58±7.13ab 94.65±5.12a 90.00±6.49b 93.07±2.34ab
Pelt weight, g 665.67±83.92a 675.71±89.31a 678.08±68.54a 594.17±92.11a 632.86±66.15ab
Density of guard hair and fiber, root/cm2 1839.57± 597.20ab 1957.76± 572.36a 1883.16± 675.70ab 1303.64± 187.97c 1387.51 ± 277.49bc
Average length of under hair, cm 5.70±0.41bc 6.07±0.33a 5.86±0.36ab 5.62±0.53bc 5.34±0.78c
