Fattening Pigs with Tannin-Rich Source (Ceratonia siliqua L.) and High Doses of Vitamin E: Effects on Growth Performance, Economics, Digestibility, Physiology, and Behaviour

Abstract

This study aimed to assess the impact on growth, economic results, apparent nutrient digestibility (CTTAD), physiological variables, and animal behaviour when 214 fattening pigs (78 ± 8.5 kg of initial body weight and 130 ± 4.5 days of age) of both sexes (gilts and boars) were fed two levels of carob pulp (Cp, 0 vs. 20%) and two doses of vitamin E (Vit E, 30 vs. 300 IU/kg) for 40 days. No interaction effects between factors studied (Cp, Vit E, and sex) were observed on the variables. Most productive traits were unaffected by Cp or Vit E inclusion. However, the Cp increased the feed conversion ratio during the first 20 days. The Cp group showed a higher CTTAD of ether extract and hemicellulose but lower CTTAD of crude protein. Pigs fed Cp had a lower plasmatic urea content than the control group. The high Vit E doses increased the CTTAD of every nutrient and the plasmatic α-tocopherol content. The pigs fed Cp tended to spend more time eating in the early morning, likely to mitigate tannins' astringent effects. Dietary inclusion of 20% Cp in finishing high-conformation pigs is possible without affecting overall performance though it reduces nutrient CTTAD and increases feeding cost. Supra-nutritional doses of Vit E do not affect pig performance but increase the α-tocopherol deposition with potential antioxidant effects.

Keywords: carob pulp; condensed tannin; palatability; polyphenol; α-tocopherol.

Figure 1

Effects of dietary inclusion of carob pulp (0 vs. 20%) and supra-nutritional doses of vitamin E (30 and 300 IU/kg) on the time budget spent (%) in maintenance (eating and drinking) and social behaviours (positive and agonistic interaction) of fattening pigs (gilts and boars). ^†, p < 0.10; * p < 0.05; ** p < 0.001.

Figure 2

Canonical discriminant analysis of four experimental diets with 0 or 20% carob pulp (Cp) and 30 or 300 IU/kg of vitamin E, indicated as follows: 0% Cp and 30 IU Vit E (grey triangles), 0% Cp and 300 IU Vit E (grey circle), 20% of Cp and 30 IU Vit E (black triangle), and 20% of Cp and 300 IU Vit E (black circle). Variable correlations with the discriminant functions are represented by black straight lines and blue squares. Function 1 (Can 1) accounted for 56.0% of the total variation among feeding strategies and it was determined by the CTTAD of CP (r = 0.72), CTTAD of hemicellulose (r = −0.45) and the CTTAD of EE (r = −0.25). Function 2 (Can 2) accounted for 43.8% of the variance and it was determined by plasma α-tocopherol content (r = 0.78) and carcass weight (r = −0.37). DM, dry matter; ADG 151–169, average daily gain from 151 to 169 days of age.