Nutritive value and digestibility of macronutrients from sheep and alpaca skin hydrolysates as a new alternative in juvenile rainbow trout (Oncorhynchus mykiss) feeding

Abstract

Background The protein source from fish meal is very important in trout feeding, but it is expensive and very scarce. Alternative nutrient sources are required to achieve sustainability as trout production rapidly grows in Peru. The objective of this research was to determine the proximate chemical composition and the apparent digestibility coefficient (ADC) of dry matter, organic matter, crude protein, crude fat, and digestible energy of hydrolyzed sheep (HSS) and alpaca (HSA) skins in juvenile rainbow trout. Methods A total of 450 fishes were randomly distributed in nine digestibility tanks, with 60.0 ± 1.32 g of initial weight and 6.4 kg/m3 of stocking density. The water quality parameters were as follows: pH 8.4, temperature 11.5 °C, and dissolved oxygen 6.2 mg/l. The skin hydrolysates were treated at 130 °C with 15 psi pressure for 120 min. Fish were fed a reference diet and an experimental diet containing 70% reference diet and 30% skin hydrolysate. The ingredients of the diets were mixed and then extruded at 95 °C with 4-mm diameter (Extruder Khal® EE800). The ADC was determined by the indirect method using insoluble ash as a non-digestible marker. Results The ADC in HSS and HSA was similar for dry matter (67.7 vs 69.1%), organic matter (66.9 vs 68.2%), crude protein (70.4 vs 70.1%), and digestible energy (3.35 vs 3.24 Mcal/kg DM), but crude fat values were different (12.3 vs 48.0%; p < 0.001, respectively). Conclusion The hydrolyzed sheep and alpaca skins had a high content of macronutrients with an acceptable apparent digestibility of nutrients, making them a viable alternative to improve the nutritive value of more economical feeds for rainbow trout feed.

Productive performance and some physiological parameters of Japanese quail-fed diets supplemented with different levels of white shaving protein wastes.

“…In this context, León-López et al (2019) indicated that collagen is characterized by a high concentration of three major amino acids, glycine, proline, and hydroxyproline, which create its characteristic triple helix structure. Also, Araníbar-Araníbar et al (2020) indicated that the hydrolyzed sheep and alpaca skins have a high content of macronutrients with acceptable digestibility of the nutrients, making them a viable alternative to improve the nutritional value of rainbow trout rations. In addition, results of Iwai et al (2005) showed that the collagen is enzymatically hydrolyzed, and this breaks it down into smaller peptides (the primary complementary form of collagen) that are easily absorbed within the digestive tract before entering the circulation.…”

Respuesta productiva de truchas arcoíris (Oncorhynchus mykiss) al régimen alimenticio con alimentos comerciales bajo condiciones de crianza intensiva en el Lago Titicaca

“…Productive response of rainbow trout (Oncorhynchus mykiss) to the feeding regime with commercial feeds under intensive farming conditions in Lake Titicaca Marina Flores M. 1 , Rosario E. Ortega B. 2 , María del Pilar Blanco E. 3 , Marcelino J. Araníbar 4 *…”