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Slaughtering heavy pigs optimize the high rates of weight gain achieved by selected animals and reduce operating costs both to the farm and the slaughterhouses. However, finishing phase is quite costly to pig farmers especially due to the high volume of feed required in a lower efficiency rate. There is a lack of information regarding the recommended level of net energy (NE) for heavy pigs, especially with reduced crude protein (CP) diets. The objective of this study was to investigate different NE levels with reduced CP (that were supplemented with amino acids) on feeding behavior, performance and carcass characteristics of heavy pigs (100–130 kg). Sixty-five barrows (100 ± 6.0 kg of BW) were randomly allotted to experimental groups under a randomized complete block design with initial body weight as the blocking criterion. There were 5 treatments (NE levels: 2300, 2388, 2475, 2563 and 2650 Kcal NE/kg, as-fed basis) with 13 pigs per treatment (penned individually), and the animal was the experimental unit. The diets were based on corn, soybean meal and wheat bran and provided for 32 d. The CP levels were similar between diets and approximately 2% below the requirement (13.9%). Pigs were weighed at the beginning and end of the experiment. The visits to the feeders, the timing of meals, and the amount of feed consumed per meal were recorded with automatic feeding stations. The daily feed intake was calculated and feeding behavior was evaluated. At the end of the experiment, the pigs were slaughtered for carcass evaluation.
Net energy levels did not affect the average daily feed intake but did influence the feeding behavior of the pigs. The pigs fed the 2388, 2475 and 2563 kcal NE/kg diets had fewer daily meals than those fed the 2300 and 2650 kcal NE/kg diets. Thus, these animals occupied the feeders for less daily time compared to those fed 2300 and 2650 kcal NE/kg. The average daily intake of NE increased linearly with increasing NE; however, average daily gain did not differ across dietary treatments. The feed efficiency showed a quadratic relationship with increased NE levels. The feed efficiency of pigs fed 2563 kcal NE/kg did not differ from those fed 2388 and 2475 kcal NE/kg treatments but was 9% higher than in the 2300 and 2650 kcal NE/kg treatments. Furthermore, the loin depth and loin eye area did not change significantly when NE levels increased from 2300 to 2650 kcal NE/kg in the diets. Nevertheless, a linear effect was observed for hot carcass yield and a tendency toward a quadratic effect for hot carcass weight, backfat thickness and lean percentage.
In conclusion, across the dietary levels studied, 2388, 2475 and 2563 kcal NE/kg produced the best results for reduced CP diets provided to heavy pigs for 32 d because the pigs occupied the feeders for less time and showed increased feed efficiency.
Fracaroli, C., Perondi, D., dos Santos, L. S., da Silva, W. C., Veira, A. M., & Hauschild, L. (2017). Net energy levels of reduced crude protein, amino acid-supplemented diets for heavy pigs. Livestock Science, 205, 43-49. https://doi.org/10.1016/j.livsci.2017.09.014
