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Energy requirement of growing pigs under commercial housing conditions a

a

Maike Naatjes & Andreas Susenbeth a

Institute of Animal Nutrition and Physiology, Christian-AlbrechtsUniversität zu Kiel, Kiel, Germany Published online: 20 Mar 2014.

To cite this article: Maike Naatjes & Andreas Susenbeth (2014) Energy requirement of growing pigs under commercial housing conditions, Archives of Animal Nutrition, 68:2, 93-110, DOI: 10.1080/1745039X.2014.887814 To link to this article: http://dx.doi.org/10.1080/1745039X.2014.887814

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Archives of Animal Nutrition, 2014 Vol. 68, No. 2, 93–110, http://dx.doi.org/10.1080/1745039X.2014.887814

Energy requirement of growing pigs under commercial housing conditions Maike Naatjes and Andreas Susenbeth*

Downloaded by [Northeastern University] at 15:18 16 November 2014

Institute of Animal Nutrition and Physiology, Christian-Albrechts-Universität zu Kiel, Kiel, Germany (Received 24 May 2013; accepted 14 January 2014) Scientifically derived recommendations for the energy supply to growing pigs are generally based on estimates of the metabolisable energy (ME) requirements for maintenance (MEm) and protein (MEp) and fat (MEf) retention. It is supposed that animals are kept within the zone of thermoneutrality and that their physical activity is not elevated. These assumptions might not always be true for practical housing conditions, and it is difficult to quantify the additional energy needed for thermoregulation and physical activity. Hence, at a given ME intake, differences can occur between the actual growth rates and those predicted from the recommendations. To quantify such differences, three trials were carried out under commercial farming conditions with pigs growing from 25 to 120 kg body weight (BW). In each trial, 624 castrated male and female pigs were allocated to four feeding groups distributed over 24 double pens. The rations were provided according to the animals’ feed intake capacity and BW was recorded every three weeks. Protein, fat and energy retention (RE) was derived from carcass composition and BW gain. The difference between ME intake and MEm plus ME required for growth (MEg = RE/kpf) was calculated and seen as the ME required for purposes other than maintenance and growth (MEx). MEx accounted for 2.0%, 17.0% and 21.4% of the animals’ ME intake in Trials 1, 2 and 3, respectively, and was higher in female than in castrated male pigs when related to metabolic BW. It was concluded that total ME requirements of pigs kept under commercial housing conditions can be considerably higher than ME requirements predicted from feeding standards since they usually ignore MEx. MEx can be used as an indicator for the quality of housing systems. Further studies are needed to identify the key factors responsible for MEx to allow for more precise recommendations for the energy supply to commercially raised pigs. Keywords: commercial farming; energy requirements; feeding standards; growth; pigs

1. Introduction Feed costs generally account for more than half of total cost in livestock production. According to estimates of commercial feed mills (personal communication), the supply of metabolisable energy (ME) to animals accounts for 70–80% of the total feed cost. Therefore, a reduction in the amount of ME required per unit produced is a key factor for economical productivity and an improved utilisation of feed resources. In growing pigs as well as in other livestock species, recommendations for an adequate energy supply are generally based on a factorial approach, which relies on estimates of the energy requirements for maintenance and growth (ARC 1981; NRC 1998; GfE 2008). However, these estimates are commonly derived from data of balance studies performed *Corresponding author. Email: [email protected] © 2014 Taylor & Francis

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under experimental housing conditions, where animals are kept individually in metabolic cages. At a similar feed intake, animal performance in these studies might be higher than under commercial housing conditions due to good climatic and hygienic conditions, the absence of social stress and/or a lower physical activity. Correspondingly, e.g. Black et al. (1999) observed 20–30% lower growth rates in pigs raised under commercial conditions than those raised in experimental trials. It is unlikely that variations in the efficiency of energy utilisation for growth (kpf) are responsible for those differences, since energy retention (RE) is linearly related to energy intake, which means that kpf did not change with the level of growth rate (Noblet et al. 1999), age, gender and genotype (Susenbeth 1996). Furthermore, partial efficiency of ME utilisation for RE was not altered by chronic immune system activations (Williams et al. 1997). Similarly, only minor variations in the efficiency of amino acid utilisation when being firstlimiting were observed (Susenbeth 1995; Sandberg et al. 2005). Neither body weight (BW) (Dunkin and Black 1985), genotype (Kyriazakis et al. 1995), nor environmental temperature (Wellock et al. 2003) affected the response of protein retention to energy supply in energy limited diets. Hence, it appears that lower performance of animals under commercial housing conditions is mainly caused by their higher energy demand for physical activity, thermoregulatory heat production and/or social stress, which reduce the amount of energy available for growth. The aim of this study was therefore to quantify the difference between the ME intake of growing pigs kept under commercial housing conditions and their ME requirements for maintenance and growth. These differences were determined in castrated male and female animals at several growth stages. The concept of this procedure is similar to the so-called residual feed intake concept (e.g. Gilbert et al. 2007); however, it is based on the principles of energy metabolism in growing animals and a precise description of all necessary information and figures is provided in this study to give full traceability.

2. Material and methods 2.1. Animals and housing Three trials (Trials 1, 2 and 3) were performed on a commercial livestock farm in 2004– 2005. In each trial, 624 animals were used with a mean initial BW of 25.3, 25.4, and 34.2 kg, respectively (Table 1). Pigs were of the genetic line German PIC × Pietrain in Trial 1, while Danish crossbreed pigs of Landrace × Yorkshire and Pietrain were used in Trials 2 and 3. The animals were randomly distributed among 24 double pens with either 26 castrated male or 26 female pigs each. The double pens were sub-divided by one long feeder into two single pens of 4.5 · 2 m2, equivalent to 0.7 m2 per animal. Since 35 cm of feeder space was available to each pig, all animals could eat simultaneously during feeding. Slurry was stored 1.8 m below the pens and was kept in circulation. The stable was ventilated by a low-pressure system that distributed the air through eight 4 × 10 m2 permeable reed mattings. A climate logger continuously recorded humidity and air temperatures in and outside the rooms in order to adjust air conditioning and heating. Mean daily temperature and humidity across all trials was 20.4°C and 56%, respectively (minimum 44%, maximum 69%). Air temperature ranged between 17.6°C and 26.3°C, 18.1°C and 27.8°C, and 16.4°C and 21.8°C in Trials 1, 2 and 3, respectively. In the respective growing periods, it was never below the minimum ambient temperatures recommended for growing pigs of ≤60 kg (19.5°C) and ≥60 kg BW (13–15°C; GfE 2008) and only exceeded the recommended maximum comfortable temperature of 24°C (Mayer and Hauser 1999) during less than 5% of the total growing period.

Note: *RMSE, Root mean square error.

25.7 54.9 74.8 95.0 111.2 116.4 92.0 53.9

Castrated male

Trial 1

24.9 51.5 70.8 88.6 104.8 116.3 91.9 57.4

Female 25.9 53.1 69.5 86.8 102.8 116.2 91.7 53.3

Castrated male

Trial 2

25.2 50.3 65.4 80.7 95.8 112.6 89.0 56.8

Female 33.9 57.9 74.6 94.2 110.2 115.9 91.6 54.4

Castrated male

Trial 3

34.4 58.9 75.7 93.2 108.6 117.1 92.5 56.3

Female 2.249 2.642 3.255 3.215 3.405 2.996 2.329 1.064

RMSE*

Energy requirement of growing pigs under commercial housing conditions.

Scientifically derived recommendations for the energy supply to growing pigs are generally based on estimates of the metabolisable energy (ME) require...
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