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.
Three trials involving 396 pigs were conducted to determine the effects of regrouping finishing swine (83.8 +/- .69 kg) on weight gain and behavior during the subsequent 2-wk period. The methodology between Trials 1, 2, and 3 differed primarily in the total number of pigs tested (72, 144, and 180, respectively) and the number of pigs per pen (3, 3 or 5, and 5, respectively). In all trials, like-sexed pigs were moved into a new pen location and allotted to one of three treatments: 1) a group of familiar pen mates (Control), 2) a group composed of unfamiliar pigs (Mixed), and 3) pigs mixed with strangers for 24 h and then reunited with original pen mates for the duration of the trial (Mixed 24 h). In the pooled analysis, control pigs gained faster (P < .01) than Mixed pigs (.87 and .77 kg/d, respectively) over the 2-wk period. Mixed 24-h pigs were intermediate in gain (.80 kg/d), indicating that the most severe aggression normally observed during the first 24 h accounts for only a portion of the setback. Apparently the negative social stress associated with being in the presence of unfamiliar pigs persisted beyond the first 24 h and was sufficient to limit weight gain over the 2-wk period. Time spent fighting was reduced from 1.72 min/h during a 6-h period on d 1 to .39 min/h during a 3-h period by d 2 in the Mixed group. Fighting was still observed in the Mixed pens 8 d after regrouping (.23 min/h), indicative of ongoing social conflicts.(ABSTRACT TRUNCATED AT 250 WORDS)
A sequential elimination trial was conducted to test the effects of primary tastes on the preference ranking of TMR diets by six multiparous Holstein cows from 8 to 21 DIM. Four additives and a control were examined; the most preferred (highest total intake) was eliminated after segments of 5, 4, 3, and then 2 d. Diets tasting sweet (sucrose, 1.5% of dietary DM), sour (HCl, 1.25%), bitter (urea, 1%), and salty (NaCl, 4%) were tested. Four of the cows most preferred the sweet diet, and DMI of that diet averaged 12.8% more than for the control, which was next preferred. The probability of a diet being chosen first when all diets were presented together was sucrose, .59; control, .36; urea, .04; NaCl, .01; and HCl, .003. Another experiment used the same procedure; however, the additives tested were anise, monosodium glutamate, dehydrated alfalfa meal flavor, and molasses flavor (1.48 g of flavor/kg of DM). Control and monosodium glutamate ranked first equally. The probability of choosing each flavor first in this set was .5 for the control and monosodium glutamate diets and < .01 for molasses, alfalfa, and anise. Rankings were not significantly affected by variation among cows in either experiment. Of the additives tested, only sucrose seemed to have the potential to increase intake.
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