Effects of replacing marine fishmeal with graded levels of Tra Catfish by-product protein hydrolysate on the performance and meat quality of pigs

Nt Thuy,Nc Ha,M Joseph

doi:10.4314/sajas.v46i3.1

Abstract

A feeding trial was carried out to evaluate the effects of replacing fish meal (FM) with Tra Catfish (Pangasius hypophthalmus) by-product protein hydrolysate (TPH) on performance and carcass quality in pigs. Forty crossbred castrated (Yorkshire x Landrace) male pigs with an initial average bodyweight of 22.8 ± 1.5 kg were allocated to 40 individual pens in a randomized complete block design with eight replications. The pigs were fed a control diet (TPH0) with FM as sole protein supplement. In the experimental diets, 100% (TPH100), 75% (TPH75), 50% (TPH50) and 25% (TPH25) of the crude protein (CP) from FM was replaced by the CP from TPH. The results showed no significant differences in average daily feed intake (ADFI) in all treatments during the growing and finishing phases. However, daily weight gain (ADG) was higher in TPH75 (655 g/day) and TPH100 (663 g/day) than in TPH0 (639 g/day). Feed conversion ratio (FCR) was improved with higher inclusion of TPH in the diets. Carcass yield and dressing percentage were not affected by treatments, but abdominal fat and backfat thickness were higher and in the loin-eye area lower in TPH100 compared with TPH0. Polyunsaturated fatty acids (PUFA), ether extract (EE) contents and meat colour values a* (redness) in the longissimus dorsi muscle increased with TPH replacement level. Feed costs were 10% lower in TPH100 compared with TPH0. In conclusion, replacing FM with TPH improved the performance, but resulted in an increase in backfat thickness and fat content of meat. However, because of reduced feed costs, complete replacement of FM would still be profitable for pig producers in Vietnam.Keywords: Backfat thickness, longissimus dorsi muscle, fatty acid, Pangasius hypophthalmus

Highlights

Pangasius hypophthalmus (Vietnamese Tra Catfish) is considered the major fish species of the country, and contributes significantly to socio-economic development through exporting the processed fillet (Minh, 2014)
The pigs were weighed at the beginning and end of each phase, feed intake was recorded, and Feed conversion ratio (FCR) was calculated as feed intake divided by weight gain
Protein hydrolysate quality from Tra Catfish by-product varies according to the proportions of the initial by-product composition, resulting in a difference in crude protein (CP) content

Summary

Introduction

Pangasius hypophthalmus (Vietnamese Tra Catfish) is considered the major fish species of the country, and contributes significantly to socio-economic development through exporting the processed fillet (Minh, 2014). Tra Catfish by-products, which include head, bone, skin, scrap meat and the abdominal organs, are ground fresh, boiled, the oil extracted, and dried to produce catfish by-product meal in commercial processing companies (Thuy et al, 2011). In the process, large volumes of wastewater are discarded, resulting in environmental pollution. This is a wasted protein resource that is not normally used in pig diets. This wastewater by-product can be converted into Tra Catfish by-product protein hydrolysate (TPH) by adding enzyme papain, followed by mixing with solid matter and drying to powder to produce the catfish by-product of protein hydrolysate (TPH). The major components after hydrolysis of the by-product are peptides with different molecular weights (Thuy et al, 2015)

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