Impact of amino acid and CP restriction from 20 to 140 kg BW on performance and dynamics in empty body protein and lipid deposition of entire male, castrated and female pigs

Abstract

Breeding leaner pigs during the last decades may have changed pig's empty body (EB) composition, a key trait for elaborating feeding recommendations. This research aimed to provide new experimental data on changes in the chemical composition of the EB of pigs from 20 to 140 kg BW. In addition, the impact of a reduction in the dietary CP associated with lower lysine, methionine + cystine, threonine and tryptophan levels was determined. In total, 48 males, castrates and females weighing 20 kg BW were allocated either to a control grower-finisher diet formulated according to current Swiss feeding recommendations, or a low CP grower-finisher diet (80% of control). Feed intake was monitored and pigs were weighed weekly. The chemical composition of EB (blood, hairs and hoofs, offals, bile, carcass) was determined at 20, 40, 60, 80, 100, 120 and 140 kg BW on four pigs per gender and diet (eight pigs per gender at 20 kg). The five fractions were weighed and samples were analysed for dry matter, protein, fat and energy. Nutrient deposition rates and N efficiency were calculated by using the 20 kg BW category as reference. Analysis revealed an accurate feed optimisation for the aforementioned essential amino acids (EAA), whereas digestible isoleucine content in the low CP diet was at 70% of the control diet. Despite similar feed intake, daily gain and feed efficiency were impaired ( P < 0.01) from 20 to 100 kg BW in the low CP compared with the control pigs. In the same growth period, castrates had the greatest feed intake but, together with females, displayed the lowest ( P < 0.01) feed efficiency. Protein deposition was reduced ( P < 0.01) by up to 31% with low CP diet and was lower ( P < 0.01) in castrates and females than males at 100 kg BW. The greatest fat deposition rates were found with low CP diet and castrates. N efficiency improved ( P < 0.05) by 10% with the low CP diet from 100 to 140 kg. The males displayed the greatest ( P < 0.05) N efficiency. These findings suggest that the CP content of finisher II diets could be reduced to 102, 102 and 104 g/kg for females, castrates and males, respectively, without a negative impact on protein deposition or growth. It remains unclear whether the negative effects found in the BW range from 20 to 100 kg on the EB deposition were due to the 20% reduction of the dietary CP and the five limiting EAA or to other EAA via an unbalanced EAA profile.

Effect of Free-Range and Low-Protein Concentrated Diets on Growth Performance, Carcass Traits, and Meat Composition of Iberian Pig

“…No dietary effect on ADG between LP and SP groups was observed, in accordance with previous studies in Alentejano (Iberian) pigs [31] and in heavy pigs [32][33][34][35]. In contrast, other authors found that feeding pigs ad libitum with protein-or lysine-deficient but adequate-energy diets during the finishing phase reduces ADG rate [36][37][38]. Differences between the abovementioned studies could be explained by the different growth rates of the pig breed [6], the pig body weight when the protein restriction is carried out [38], and the deficiencies in protein and essential amino-acid levels [31].…”

Dynamics of the mineral composition and deposition rates in the empty body of entire males, castrates and female pigs

“…Animals, experimental diets and design A detailed description of the experimental design, diets and management protocol was previously presented by Ruiz-Ascacibar et al (2017). In brief, a total of 190 Swiss Large White pigs (66 FE, 66 EM and 58 CA) were used which originated from four farrowing rounds from the Agroscope sow herd.…”

“…In both treatments, the grower, finisher I and II diets for EM contained 5% more digestible CP, digestible lysine, methionine + cystine, threonine and tryptophan than the diets for FE and CA. The diet formulation, as well as, the analyzed contents of crude fat, crude fibre, ADF, NDF, CP and amino acids are outlined by Ruiz-Ascacibar et al (2017). Diets were produced at the Agroscope experimental feed mill and were pelleted (60°C, 4 mm diameter).…”

“…The serial slaughter method, sampling and grinding procedures were detailed by Ruiz-Ascacibar et al (2017). In brief, when the individual pigs reached their target BW for slaughter, they were fasted for~16 h, stunned with CO 2 and exsanguinated.…”

“…The analyzed major nutrient concentrations, including CP and amino acids are described by Ruiz-Ascacibar et al (2017) and the CP, ash, macro-and trace mineral concentrations of the experimental diets are shown in Table 1. The dietary mineral concentrations were consistent with expected values, except that Ca concentration in the starter and grower diets were 5% to 7% lower than expected.…”