Abstract
The present study was carried out to evaluate the effect of net energy levels in diets for barrows, from 70 to 100 kg, on performance, plasma parameters and carcass characteristics. Two experiments were carried out: in the first (Experiment I), a metabolism assay was carried out to estimate the net energy (NE) of experimental diets. Twelve crossbred barrows, averaging 85.74 ± 6.80 kg initial body weight, were distributed in a randomized block design with two metabolizable energy (ME) levels (3100 and 3500 kcal kg–1) with six replicates and one animal per experimental unit. In the second (Experiment II), 45 castrated male pigs were used, averaging 70.10 ± 1.26 kg of initial body weight distributed in a randomized block design, with five NE levels (2345, 2425, 2505, 2585, 2665 kcal kg–1), nine replicates and one animal per experimental unit. The increase in diet NE levels provided a linear reduction (p ≤ 0.00039) in average daily feed intake (ADFI). There was a quadratic effect on NE efficiency (p ≤ 0.0027), average daily gain (ADG), (p ≤ 0.0352) and the feed:gain ratio (F:G), (p ≤ 0.0024), the optimal levels being estimated at 2485, 2493 and 2533 kcal kg–1, respectively. Drip loss (DL) decreased (p ≤ 0.0001) as NE levels increased. There was also a linear decrease (p ≤ 0.0462) in the Minolta color parameter (+a*), due to the NE levels. Plasma parameters were not affected (p > 0.05) by NE levels. The dietary net energy levels affected the performance and meat quality of finishing pigs and the level of 2493 kcal kg–1 provided the best ADG.
Highlights
On swine farms in Brazil, the diets are usually formulated based on metabolizable energy (ME)
There was a quadratic effect on net energy (NE) efficiency (p ≤ 0.0027), average daily gain (ADG), (p ≤ 0.0352) and the feed:gain ratio (F:G), (p ≤ 0.0024), the optimal levels being estimated at 2485, 2493 and 2533 kcal kg–1, respectively
The differences between the ME and NE systems are in the energy expenditure associated with diet heat increment (HI), which can be defined as the heat generated by metabolic processes during nutrient absorption and metabolization
Summary
On swine farms in Brazil, the diets are usually formulated based on metabolizable energy (ME). The use of digestible energy (DE) and ME in diet formulation may overestimate protein and fiber digestibility (Weber et al, 2010), or underestimate starch and fat digestibility (Noblet et al, 1994; Noblet, 2007). In this context, the use of NE can be observed in several countries, still considered as the most accurate energy system for swine production. This energy can be dissipated into the environment or used to maintain body temperature on cold days (Kil et al, 2013; Moehn et al, 2013)
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