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Effect of Enzymes in Wheat and Canola Meal Diets

by 5m Editor
15 January 2004, at 12:00am

By Ruurd T. Zijlstra, Shaoyan Li, and John F. Patience - Carbohydrases in 25% canola-meal diet consumed freely by weaned pigs: increased daily gain (up to 13%), increased feed intake (up to 16%), did not affect feed efficiency, reduced viscosity of digesta in ileum, and did not affect nutrient digestibility.

Summary

Beneficial effects of enzyme supplementation to a wheat-canola meal diet fed to weaned pigs were not related to improved nutrient digestibility, but rather to increased feed intake. The increase in feed intake is hard to explain directly. However, reduced viscosity of digesta in the distal small intestine suggests that increased feed intake is related to an increased passage rate.

Introduction

The nutritional value of canola meal for pigs is lower than soybean meal (SBM). The digestible energy (DE) content is 14% lower in canola meal than in SBM. Gross energy (GE) content of canola meal is similar to SBM; but high concentrations of fibrous components seem to limit digestibility and availability of energy. Crude fibre content is three times higher in canola meal than in SBM. The NSP concentration in canola meal is high, with cellulose and arabinose as the major components.

Supplemental enzymes are becoming popular to overcome limitations of pigs to digest NSP such as ß-glucans and arabinoxylans. In pigs, faecal digestibility of NSP and the nutrients they enclose is higher than ileal digestibility, because of microbial degradation in the hindgut. Energy and protein fractions digested in the large intestine have less metabolic value compared to nutrients digested and absorbed in the small intestine. Thus, supplemental enzymes to degrade NSP might improve digestibility of NSP and the enclosed nutrients at the ileum and thereby increase nutrient utilisation.

The objective of this study was to improve the nutritional value of a canola meal diet for weaned pigs with supplemental enzymes.

Experimental Procedures

Ninety-six 21-day-old pigs (48 barrows and 48 gilts) were weaned at 3 weeks and housed in an all-in-all-out nursery with slotted floors. For 7 days, pigs had free access to a regular phase-1 diet.

After acclimation, six pens were assigned to four diets for 28 days, for 24 pigs per diet. A wheat-canola meal diet was formulated to contain 3.15 Mcal DE/kg and a digestible lysine to DE ratio of 3.35 g/Mcal (Figure 1). Vitamins, minerals and amino acids were supplemented to meet nutrient requirements. Chromic oxide was included to mark digestibility. An enzyme premix (Finnfeeds International) containing ß-glucanase and xylanase was added to the basal diet at 0, 1, 2 and 4 g/kg to create four experimental diets. Pigs had free access to feed and water. Diets were offered in mash form.

To study growth performance, pigs were weighed at weaning, and every 7 days until the end of the experiment. Feed intake was measured every 7 days.

To study nutrient digestibility, 6 pigs per diet were euthanised to collect digesta. Digestibility was studied in small intestine digesta as opposed to in faeces, because total tract digestibility might conceal effects of supplemental enzymes. To mimic commercial practice and maximise feed intake, pigs were not cannulated but slaughtered to collect digesta. Immediately after digesta collection, pH and viscosity were determined. Diet and digesta were analysed for DM, ADF, NDF, chromium oxide, and GE. Nutrient digestibility was calculated using chromium oxide concentrations in diets and faeces.

Results and Discussion

Performance. Average daily gain (ADG) increased quadratically (P < 0.05; Figure 2) for the entire experimental period. Numerically, pigs fed the diet supplemented with 2 g enzyme/kg diet had the highest ADG. Supplementation of 2 g enzyme/kg diet increased ADG 53 g/d (13%) compared to the control diet (P < 0.05). More specifically, ADG increased quadratically for days 8-14 (P < 0.05). Treatment differences were not observed for other weeks.

Average daily feed intake (ADFI) of weaned pigs increased quadratically (P < 0.05; Figure 2) for the entire experimental period. Numerically, pig fed the diet supplemented with 2 g enzyme/kg diet had highest ADFI. Supplementation of 2 g enzyme/kg diet increased ADFI 100 g/d (15%) compared to the control diet (P < 0.05). More specifically, ADFI increased quadratically for days 1-7 (P < 0.10) and days 8-14 (P < 0.05) and linearly for days 1-7 (P < 0.10) and days 22-28 (P < 0.10). For days 15-21, dietary treatments were not different.

Feed efficiency was altered by enzyme supplementation for the entire experimental period (P > 0.10). Only for days 1-7, feed efficiency was reduced linearly (P < 0.05; Figure 3) with an increase in enzyme supplementation.

Nutrient digestibility. Enzyme supplementation did not alter nutrient digestibility for any section of the small intestine (Figure 4). Digestibility of NDF improved linearly with enzyme supplementation (Figure 4; P < 0.12). Digestibility values for ADF were low and the negative digestibilities suggests that pigs failed to utilise ADF even with supplemental enzymes.

Enzymes did not alter digesta pH. Viscosity was 30% reduced at the ileum with enzyme supplementation at 4 g/kg (P < 0.05; Figure 5).

Implications

The results of the present study indicate that nutritional value of wheat-canola meal diets can be improved by enzyme supplementation by increasing feed intake. This study studied effects of enzymes on nutrient digestibility in weaned pigs with free access to feed. Data indicated that nutrient digestibility was not affected by enzymes.

Acknowledgements

The authors acknowledge the financial assistance for the project provided by the Canola Council of Canada, Finnfeeds International, Saskatchewan Canola Development Commission, and the Program for Export Market Development. The pork producers of Saskatchewan, Manitoba and Alberta are acknowledged for their strategic funding to Prairie Swine Centre Inc.

Figure 1: Composition of the control diet

* ASP 250, Vit . + Min. mix, Salt, L-Lys, L-Thr, L-Trp. Choline chloride

Figure 2: Average daily gain and daily feed intake of weaned pigs fed
wheat-canola meal diets supplemented with carbohydrases


*;P < 0.05

Figure 3: Feed efficiency of weaned pigs fed wheat-canola
meal diets supplemented with carbohydrases


Figure 4: Digestibility of NDF and energy in small intestine digesta collected from
weaned pigs fed wheat-canola meal diets supplemented with carbohydrases.


Figure 5: pH and viscosity NDF and energy in small intestine digesta collected from
weaned pigs fed wheat-canola meal diets supplemented with carbohydrases.


*;P < 0.05

December 2003