title: Application of broken-line analysis to assess floor space requirements of nursery and grower-finisher pigs expressed on an allometric basis.
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.
authors.affiliation: Prairie Swine Centre, Inc., Saskatoon, Saskatchewan, S7H 5NP, Canada. gonyou@sask.usask.ca
authors.forename: H W
authors.initials: HW
authors.lastname: Gonyou
authors.forename: M C
authors.initials: MC
authors.lastname: Brumm
authors.forename: E
authors.initials: E
authors.lastname: Bush
authors.forename: J
authors.initials: J
authors.lastname: Deen
authors.forename: S A
authors.initials: SA
authors.lastname: Edwards
authors.forename: T
authors.initials: T
authors.lastname: Fangman
authors.forename: J J
authors.initials: JJ
authors.lastname: McGlone
authors.forename: M
authors.initials: M
authors.lastname: Meunier-Salaun
authors.forename: R B
authors.initials: RB
authors.lastname: Morrison
authors.forename: H
authors.initials: H
authors.lastname: Spoolder
authors.forename: P L
authors.initials: PL
authors.lastname: Sundberg
authors.forename: A K
authors.initials: AK
authors.lastname: Johnson
mesh_terms: D000822:Animal Husbandry; D000827:Animal Welfare; D000818:Animals; D001835:Body Weight; D005430:Floors and Floorcoverings / Q000592:standards*; D006799:Housing, Animal; D013552:Swine / Q000254:growth & development*