Ileal and total tract nutrient digestibility in blue foxes (Alopex lagopus) fed extruded diets containing different protein sources

Abstract

This study compared apparent ileal and total tract digestibility of macronutrients and amino acids in blue foxes (Alopex lagopus) fed dry extruded diets. The control diet contained fish meal as the main protein source, while in the other diets 50% of the fish meal protein was replaced by not de-hulled solvent-extracted soybean meal, meat meal or bacterial protein meal. Ileal digestibility was obtained with animals modified with ileorectal anastomosis (IRA method). There were no significant differences in the average digestibility of CP, Lys, Trp, Val, Ala or Glu between IRA modified and intact animals. Average ileal digestibilities of His, Thr, Asp, Cys, Gly, Hyp, Pro, Ser, starch and total carbohydrates (CHO) were significantly lower compared with total tract values. Average ileal digestibility of Arg, Ile, Leu, Met, Phe, Tyr and crude fat was significantly higher than total tract digestibility. Digestibility measured in IRA modified animals showed less variability compared with values from intact animals. There were significant differences among diets in ileal as well as total tract digestibility of orude protein, most amino acids, starch and CHO, and in ileal digestibility of crude fat. Ileal crude protein digestibility of the diets ranged from 81.0-86.4% and total tract digestibility from 82.5-86.4%. Ileal amino acid digestibilities ranged from 70.1 (Asp) to 93.3% (Arg) and total tract values ranged from 72.8 (Cys) to 92.2% (Arg). Both ileal and total tract digestibilities of crude protein and most amino acids were significantly lower for diets containing meat meal or bacterial protein meal compared with the control fish meal-based diet and the diet with soybean meal. Although ileal digestibility may be more accurate than total tract digestibility in estimating the protein and amino acid supply in blue foxes, total tract digestibility may be acceptable because of numerically small differences between ileal and total tract digestibilities for protein and most amino acids. It was further concluded that ileal digestibilities of starch and CHO in the blue fox are lower than corresponding total tract digestibilities.

Content and apparent ileal digestibility of protein and amino acids in diets fed to parent stock of farm-raised polar foxes (Alopex lagopus L.)

“…Moreover, threonine and tryptophan also had relatively low digestibility coefficients to the end of the small intestine regardless of the diet. Similar results were also noted previously in experiments on foxes (6)(7)(8)18), mink (5), and dogs (19,20). In all the diets examined in the present study, TEAA had higher ileal digestibility coefficients compared to TNEAA, which confirms results obtained earlier in foxes (7,8) and dogs (19,20).…”

“…Similar results were also noted previously in experiments on foxes (6)(7)(8)18), mink (5), and dogs (19,20). In all the diets examined in the present study, TEAA had higher ileal digestibility coefficients compared to TNEAA, which confirms results obtained earlier in foxes (7,8) and dogs (19,20). This could result from the fact that protein of endogenous origin is not digested as rapidly as dietary protein (5,8).…”

“…It should be mentioned that in spite of significantly lower digestibility coefficients in diets with different animal offal, the calculated content of digestible protein and digestible AAs was considerably higher than in diets in which beef offal was the only source of protein (data not presented). To the end of the small intestine, high digestibility was found for arginine and methionine, as well as for histidine, lysine, phenylalanine, glutamic acid, and proline, which is in agreement with earlier investigations on ileally cannulated dogs and polar foxes (6)(7)(8)16,18,19). In the present research, the lowest availability in the small intestine was detected for cystine.…”

“…It was documented that the lower the digestibility of dietary protein is in the small intestine, the more protein is available for fermentation in the hind-gut and, thus, a larger difference between ileal and total tract digestibility will occur (7). Since low-quality protein is often used as a basic component of feeds for farm-raised polar foxes, the ileal digestibility method should be applied for determining the digestibility of protein and AAs in this species (7,8).…”

Nutrient digestibility in Arctic fox (Vulpes lagopus) fed diets containing animal meals

“…Ahlstrom et al (2000) and Vhile et al (2005b) also observed lower protein digestibility for diets containing meat meal. The digestibility coefficient of protein contained in standard mixed feed for foxes ranges from 78 to 86%, and usually exceeds 80% (Dahlman et al, 2002;Ahlstrom et al, 2003;Vhile et al, 2005b). …”