The influence of protein:energy value of the ration and level of feed intake on the energy and nitrogen metabolism of the growing pig

Abstract

1.The nitrogen balances of thirty-six individually-housed, entire male pigs (body-weight range 19-50 kg) were measured over 7 d periods when the animals were kept initially at an environmental temperature of 22O and then at loo while fed on rations containing 153, 201 and 258 g crude protein (N x 6.25; CP)/kg dry matter (DM). The respective metabolizable energy (ME) contents were 16.29, 16.96 and 17.24 MJ/kg DM. Each ration was p e n at three levels, 20,35 and SO g feed/kg body-weight per d. The animals fed on the 20 and 35 g/kg feeding level were catheterized and blood samples withdrawn on two consecutive days within the N-balance periods for the determination of blood urea (BU) concentration both before and at hourly intervals for 7 h following the morning feed.2. An increase in feed intake resulted in a significant increase in N retention (NR) at each environmental temperature. However, NR as a proportion of N intake was higher the lower the protein content of the ration. With the exception of the animals fed on the low-protein ration, NR at any given feed intake was lower at loo than at 22O and these differences were reflected in the animal's body-weight gain.3. Values for the fasting N metabolism (N,), calculated from the relationship between NR and intake of digestible N (IDN), were temperature-dependent. At 22', a constant N, value of 0,255 g N/kg body-weight0 75 per d was found appropriate, while at loo N, increased with increase in protein content of the ration from 0.380 on the low protein ration to 0.533 and 0.753 g N/kg body-weight0 75 per d on the medium-and high-protein rations respectively. 4.The efficiency of N utilization (kN) reflected the differences in the relationships between NR and IDN. At 22O the relationship was curvilinear so that kN decreased with increase in both the level of feed intake and the protein content of the ration. At 10' the relationship was linear, hence k , was independent of feed intake within rations. However, it decreased from 0.909 to 0.679 as the protein content of the ration was increased.5. The concentration of BU attained a maximal value some 3-5 h after the ingestion of the feed, with the values at loo being higher than those at 22O. BU increased as the level of protein in the ration increased but decreased with the level of feed intake when dietary protein concentration was held constant. There was a significant correlation between BU and kN, indicating that BU is a useful criterion for assessing the efficiency of N utilization.

The effect of dietary protein content and feeding level on the rate of protein deposition and energy utilization in growing Iberian pigs from 15 to 50 kg body weight

“…The intercept of equation 4 estimates daily endogenous N losses as 0·291 g/kg BW 0·75 , a value somewhat higher than the mean estimate (0·255 g/kg BW 0·75 per d) reported by Berschauer et al (1983). The value of 0·483 g digestible N/kg BW 0·75 calculated for N for maintenance by equation 4 is greater than the mean value of 0·307 g/kg BW 0·75 per d published by Berschauer et al (1983).…”

NMR-based metabolomics highlights differences in plasma metabolites in pigs exhibiting diet-induced differences in adiposity

“…The observation of a lower plasma concentration of urea in HF pigs compared with LF pigs further corroborates this statement. This reduction in plasma urea concentration may be associated with a lower protein catabolism or alternatively with an increase in the efficiency of nitrogen utilization [37] when feeding a high-fat, high-fibre diet. Similarly to our results, hyperlipidaemia induced by a high-fat diet was associated with a lower plasma level of tyrosine in rats [38,39].…”

The influence of protein:energy value of the ration and level of feed intake on the energy and nitrogen metabolism of the growing pig

“…1980). However, at similar rates of protein intake, P was greater the lower the protein content of the ration in association with a higher ME intake and an increase in the efficiency of protein utilization (Berschauer et al 1983). Thus at a protein intake of 15 g/kg b o d y -~e i g h t " '~~ per d, it was calculated that as the CP :ME content of the ration increased from 9-4 to 11.8 and 15.0 g/MJ, P decreased from 210 to 188 and 170 kJ/kg b o d y -~e i g h t~'~~ per d. There were also changes in the rate of change of P and F which were dependent upon the protein :energy relationship.…”

“…This problem has been investigated in the present experiments by determining the ME, and the k, and kF when young growing entire male pigs were fed on different concentrations of protein in the ration at constant concentrations of ME. A subsequent paper (Berschauer et al 1983) describes aspects related to the nitrogen metabolism of the animals when they were exposed to two environmental temperatures. Part of this work has been the subject of a preliminary communication (Close & Berschauer, 1981).…”