Optimización de la nutrición proteica en conejos

Abstract

[ES] Optimización del contenido en aminoácidos limitantes en dietas de engorde de conejos en función de su velocidad de crecimiento.

[EN] Nowadays, dietary protein level of fattening rabbits has been r educed to avoid frequent gastrointestinal problem s observed during this period and to minimize the environmental impact. This r eduction seems not be affecting commercial crossbred fattening rabbits, but those coming from lines highly selected for growth rate, seem to be not expressing all their genetic potential wit h under these conditions, widely affecting t he genetic rankings and consequen tly adequate genetic material diffusion. Theref ore, this thesis is an initia l attempt to determine the optimal levels of Lysine (Lys), sulphurous amino acid (Meth ionine and Cysteine) and Threonine (Thr) in function of growth rate of rab bits, through a matrix of 27 feeds and, using the Plasmatic Ureic Nitrogen (PUN ) level as a indicator of dietary amino acids imbalance. The study enrolled 432 rabbits, belonging to the R and V lines of Polytechnic University of Val encia, selected by growth rate and litter size, respectively. Each experimental fe ed was randomly assigned to each cage group of 8 rabbits, composed by animals f rom both genetic types, for a total of 27 cages per batch and two batches. The a verage daily gain (ADG) was significantly higher f or the R-line, and similarly, a verage PUN level on R line (16.43±0.19 mg/ dL; P<0.001) was greater that observed fo r the V-line (14.56±0.38 mg/dL; P<0.001). A po ssible explanation could be re lated to a greater amino acid imbalance on hi gh growth rate animals. As re gards differences on PUN level in function of dietary levels of Lys, sulphurous amino acid and Thr, average PUN reached the lowest levels for the med ium level of dietary Lys (7.3 g Lys/kg DM), as well as for the medium level of dietary sulphur amino acids (5.2 g Met/kg DM), as suggested by the literature. However, average PUN was reached the lowest level s only with the lowest dietary Thr level evaluated (5.3 g Thr/kg DM), per haps suggesting that current Th r recommendations (6.2 g Thr/kg DM) are over-estimated. These fin dings represent preliminary results; f urther research will build on t his thesis to calculate the requirements of essential am ino acid based on ADG (with 4 a dditional batches).