Application of broken-line analysis to assess floor space requirements of nursery and grower-finisher pigs expressed on an allometric basis1

Abstract

Few issues in swine production are as complex as floor space allowances. One method for pork producers to calculate floor space allowance (A) is to convert BW into a 2-dimensional concept yielding an expression of A = k * BW(0.667). Data on ADG, ADFI, and G:F were obtained from published peer-reviewed studies. Five data sets were created: A = grower-finisher pigs, fully slatted floors, and consistent group size; B = grower-finisher pigs and fully slatted floors (group size did not need to be consistent); C = grower-finisher pigs, partially slatted floors, and consistent group size; D = grower-finisher pigs, partially slatted floors (group size did not need to be consistent); and E = nursery pigs, fully slatted or woven wire floors (group size did not need to be consistent). Each data set was analyzed using a broken-line analysis and a linear regression. For the broken-line analyses, the critical k value, below which a decrease in ADG occurred, varied from 0.0317 to 0.0348. In all cases the effect of space allowance on ADG was significant (P < 0.05). Using the linear analyses based on data with k values of < 0.030, the critical k values for the 4 grower-finisher data sets did not differ from those obtained using the broken-line analysis (0.0358 vs. 0.0336, respectively; P > 0.10); however, none of the linear regressions explained a significant proportion of the variation in ADG. The slopes for the nonplateau portion of the broken-line analyses based on percent values varied among data sets. For every 0.001 decrease in k (approximately 3% of the critical k value), ADG decreased by 0.56 to 1.41%, with an average value of 0.98% for the 5%-based analyses. The use of an allometric approach to express space allowance and broken-line analysis to establish space requirements seem to be useful tools for pig production. The critical k value at which crowding becomes detrimental to the growth of the pig is similar in full- and partial-slat systems and in nursery and grower-finisher stages. The critical point for crowding determined in these analyses approximated current recommendations to ensure the welfare of pigs.

Quantitative assessment of the effects of space allowance, group size and floor characteristics on the lying behaviour of growing-finishing pigs

“…In the case of slatted floors, the proportion of variance explained by the quadratic and the broken-line regressions are the same (r 2 5 0.32); nevertheless, the threshold k 0 -value (0.039 6 0.002) obtained with the broken-line regression is relatively higher than the value of 0.032 to 0.035 found by Gonyou et al (2006) for an optimal performance of growing-finishing pigs housed either on partially or totally slatted floors. This would indicate that the expression of lying behaviour as space availability decreases may be compromised before a reduced performance becomes apparent.…”

“…In this sense, the use of broken-line regression analysis has proven to be a valuable tool in the determination of critical values when studying the effect of different characteristics of pig-housing environment on their physiology and behaviour (Huynh et al, 2005a and2005b;Aarnink et al, 2006). Broken-line analysis has been also successfully used in the determination of the critical floor space allowance for pigs' performance (Gonyou et al, 2006), suggesting that it might also be helpful in attempting to determine a critical space allowance value affecting the average time growing-finishing pigs spend lying. As the behaviour of pigs is directly related to the floor space provided, Gonyou et al (2006) suggested that consistency of behaviour over the range of weights studied should be sought, if any attempt to quantify the relationship between behaviour and space allowance was to be carried out.…”

“…Broken-line analysis has been also successfully used in the determination of the critical floor space allowance for pigs' performance (Gonyou et al, 2006), suggesting that it might also be helpful in attempting to determine a critical space allowance value affecting the average time growing-finishing pigs spend lying. As the behaviour of pigs is directly related to the floor space provided, Gonyou et al (2006) suggested that consistency of behaviour over the range of weights studied should be sought, if any attempt to quantify the relationship between behaviour and space allowance was to be carried out. Earlier studies have shown that piglets spend on average between 40% and 60% of their time resting (Blackshaw, 1981), whereas growingfinishing pigs spend, on average, 80% of their time doing so (Ruckebusch, 1972).…”

“…Allometric space allowance, expressed as m 2 /BW 0.667 , which relates the space available per pig to its scaled body weight (BW; Petherick, 1983;Baxter, 1984), provides an adequate basis -E-mail: Ludovic.Brossard@rennes.inra.fr for the determination of the spatial needs. It allows a homogenisation of all the available information according to BW, and consequently a better interstudy comparison of results within the existing literature (Gonyou et al, 2006).…”

Meta-analysis on the effects of the physical environment, animal traits, feeder and feed characteristics on the feeding behaviour and performance of growing-finishing pigs

“…This study showed that pigs are able to adapt their feeding strategy according to the group size, although the effect of group size on pigs' performance is rather limited (Turner et al, 2003). The flooring characteristics are also known to modulate the effect of physical space, temperature or housing enrichment on pigs' excretory, lying and investigative behaviours (Aarnink et al, 2006;Averó s et al, 2010a and2010b), as well as their performance (Gonyou et al, 2006). Nevertheless, the simultaneous and interactive effects of all these influences have not been estimated.…”