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A major skeletal problem of conventional- ly caged hens is increased susceptibility to osteoporosis mainly due to lack of exercise. Osteoporosis is charac- terized by a progressive decrease in mineralized struc- tural bone. Whereas considerable attention has been given to enriching laying cages, little research has been conducted on providing caged pullets with furnish- ments, in particular perches. The objective of the cur- rent study was to determine if metal perches during all or part of the life cycle of White Leghorns affected hen musculoskeletal health, especially at end of lay. Treat- ments during the pullet phase (hatch to 16.9 wk) en- tailed cages with and without perches. Four treatments were used during the laying phase (17 to 71 wk of age). Treatment 1 chickens never had access to perches at any point during their life cycle, typical of egg industry practices in the United States for conventional cages. Treatment 2 chickens had access to perches only during the egg-laying phase, which was from 17 to 71 wk of age. Treatment 3 chickens had access to perches only during the pullet phase (0 to 16.9 wk of age). Treatment 4 chickens had perch access throughout their entire life cycle (0 to 71 wk of age). Musculoskeletal health was assessed by measuring muscle weights, bone mineraliza- tion, bone fracture incidence, and keel bone deviations. Muscle deposition of 71-wk-old hens increased when given access to perches as pullets. Bone mineralization of 71-wk-old hens also increased if given perch access as adults. However, the disadvantage of the adult perch was the higher incidence of keel deviations and keel fractures at end of lay. The increase in bone mineraliza- tion of the keel bone as a result of perch access during the pullet and laying phases was not great enough to prevent a higher incidence of keel bone fractures at end of lay. Perch redesign and placement of perches within the cage to minimize keel fractures and deviations are possible solutions.

In modern poultry production systems, environmental stressors may influence bird performance and susceptibility to pathogens such as Salmonella Enteritidis. Experiments were conducted to determine the influence of 24-h feed withdrawal and 24-h exposure to high temperature (30 degrees C) on intestinal characteristics of broilers. Attachment of Salmonella Enteritidis to ileal tissue was determined using an in vitro ileal loop assay. Changes in commensal intestinal microbial populations were determined using denaturing gradient gel electrophoresis, and alterations in ileal morphology were determined histologically. Ex vivo attachment of Salmonella Enteritidis to ileal tissues increased by 1.5 logs (9.05 log10 vs. 7.59 log (10) Salmonella Enteritidis/g of ileal tissue; P = 0.0006) in broilers fasted for 24 h. Similarly, ileal tissues from birds subjected to 30 degrees C for 24 h had increased ex vivo attachment of Salmonella Enteritidis (8.77 log(10) vs. 8.50 log(10) Salmonella Enteritidis/g of ileum; P = 0.01) compared with birds held at 23 degrees C. Exposure to 30 degrees C for 24 h also altered microbial community structure in the ileum and cecum. Subjecting birds to 30 degrees C for 24 h reduced crypt depth (6.0 vs. 7.8 microm, respectively; P = 0.002), but had no effect on villus height or villus:crypt ratio. This research shows that acute stressors in poultry production systems can cause changes in the normal intestinal microbiota and epithelial structure, which may lead to increased attachment of Salmonella Enteritidis.

Enriched cages, compared with conventional cages, allow egg laying strains of chickens to meet some behavioral needs, including a high motivation to perch. The objective of this study was to determine if perch availability during rearing affected perch use as adults and if perch presence affected eating and drinking in caged White Leghorn hens. Chickens were assigned to 14 cages each with and without 2 round metal perches from hatch to 16.9 wk of age. At 17 wk of age, pullets were assigned to laying cages consisting of 1 of 4 treatments. Treatment 1 chickens never had access to perches (controls). Treatment 2 chickens only had access to 2 round metal perches during the laying phase (17 to 71 wk of age). Treatment 3 chickens only had access to 2 round perches during the pullet phase (0 to 16.9 wk of age). Treatment 4 chickens had access to the perches during both the pullet and laying phase. Each treatment during the adult phase consisted of 9 cages with 9 birds/cage for a total of 36 cages. Automatic infrared cameras were used to monitor behavior of hens in each cage for a 24-h period at 19, 24, 29, 34, 39, 44, 49, 54, 59, 64, and 69 wk of age. Behavior was also recorded twice weekly by an observer in the room where the hens were housed during photophase from 25 to 68 wk of age. Behavioral data were analyzed using ANOVA with repeated measures and the MIXED model procedure. A greater proportion of hens without perches as pullets used the rear perch more during both photophase and scotophase than hens with prior pullet perching experience. Eating and drinking activities of caged adult Leghorns were not impaired by their prior experience to perches as pullets or by the presence of perches in laying cages. It is concluded that providing perches in cages to White Leghorns during pullet rearing did not facilitate use of perches as adults.

Osteoporosis, a progressive decrease in mineralized structural bone, causes 20 to 35% of all mortalities in caged White Leghorn hens. Previous research has focused on manipulating the egg laying environment to improve skeletal health, with little research on the pullet. The objective of the current study was to determine the effect of perch access on pullet health, bone mineralization, muscle deposition, and stress in caged White Leghorns. From 0 to 17 wk of age, half of the birds were placed in cages with 2 round metal perches, while the other half did not have perches (controls). Bone mineralization and bone size traits were determined in the tibia, femur, sternum, humerus, ulna, radius, and phalange (III carpometacarpal) using dual energy x-ray absorptiometry. Muscle weights were obtained for the breast and left leg (drum and thigh). A sample of pullets from each cage was evaluated for foot health, BW, right adrenal weight, and packed cell volume. Most measurements were taken at 3, 6, and 12 wk of age. Access to perches did not affect breast muscle weight, percentage breast muscle, percentage leg muscle, bone mineral density, bone length, bone width, adrenal weight, packed cell volume, and hyperkeratosis of the foot-pad and toes. There were no differences in BW, bone mineral content, and leg muscle weight at 3 and 6 wk of age. However, at 12 wk of age, BW (P = 0.025), bone mineral content of the tibia, sternum, and humerus (P = 0.015), and the left leg muscle weight (P = 0.006) increased in pullets with access to perches as compared with controls. These results suggest that perch access has beneficial effects on pullet health by stimulating leg muscle deposition and increasing the mineral content of certain bones without causing a concomitant decrease in bone mineral density.

Two genetic lines of barrows and gilts with different lean growth rates were used to determine the BW and chemical composition growth from 23 to 125 kg of BW. The experiment was a 2 x 2 x 5 factorial arrangement of treatments in a completely randomized design conducted in 2 replicates. Six pigs from each sex and genetic line were killed at approximately 25-kg intervals from 23 kg to 125 kg of BW. At slaughter, tissues were collected and weighed. All components were ground and frozen until analyzed for water, protein, lipid, and ash. Serial BW data were fitted to alternative functions of day of age. Based on Akaike's information criteria values, the random effects model, BW(i, t) = (1 + c(i))(b(0) + b(1)t + b(2)t(2)), was the best mixed model equation. The chemical component mass data were fitted to alternative functions of BW. The allometric function, chemical component mass = aBW(b), provided the best fit to the data. Daily deposition rates of each chemical component were predicted by using the derivatives of the 2 functions. The overall ADG of the 2 genetic lines were not different. Barrows had 0.052 kg/d greater (P = 0.03) ADG than gilts. Allometric growth coefficients for all 4 chemical components were different (P0.01) for each genetic line. Allometric coefficients and predicted relative growth (g/kg of BW gain) for protein and moisture mass were greater (P0.01) for the high lean-gain pigs than the low lean-gain pigs. Allometric coefficients for lipid mass were smaller (P = 0.001) for the high lean-gain pigs than the low lean-gain pigs overall. Allometric coefficients and predicted relative growth rates for lipid mass were greater (P0.01) and for moisture and protein mass were lesser (P0.002) than the gilts. Compared with low lean-gain pigs, high lean-gain pigs had (1) 32.8% lesser predicted daily rates of lipid deposition (200 vs. 305 +/- 80 g/d), with the difference increasing from 23 to 37% from 25 to 125 kg of BW; (2) 12.3% greater daily rates of protein deposition (118.7 vs. 106.0 +/- 3.3 g/d); and (3) 18.8% greater predicted daily moisture accretion rates (423 vs. 356 +/- 9 g/d). Overall, barrows had 21.3% greater lipid deposition (279 vs. 230 +/- 78.2 g/d) than gilts. In this study, barrows and gilts had similar predicted daily moisture, protein, and ash accretion rates.

Carcass and live measurements of 45 barrows were used to evaluate the magnitude of ractopamine (RAC) treatment prediction biases for measures of carcass composition. Barrows (body weight = 69.6 kg) were allotted by weight to three dietary treatments and fed to an average body weight of 114 kg. Treatments were: 1) 16% crude protein, 0.82% lysine control diet (CON); 2) control diet + 20 ppm RAC (RAC16); 3) a phase feeding sequence with 20 ppm RAC (RAC-P) consisting of 18% crude protein (1.08% lysine) during wk 1 and 4, 20% crude protein (1.22% lysine) during wk 2 and 3, 16% crude protein (0.94% lysine) during wk 6, and 16% crude protein (0.82% lysine) during wk 6. The four lean cuts from the right side of the carcasses (n = 15/treatment) were dissected into lean and fat tissue. The other cut soft tissue was collected from the jowl, ribs, and belly. Proximate analyses were completed on these three tissue pools and a sample of fat tissue from the other cut soft tissue. Prediction equations were developed for each of five measures of carcass composition: fat-free lean, lipid-free soft tissue, dissected lean in the four lean cuts, total carcass fat tissue, and soft-tissue lipid mass. Ractopamine treatment biases were found for equations in which midline backfat, ribbed carcass, and live ultrasonic measures were used as single technology sets of measurements. Prediction equations from live or carcass measurements underpredicted the lean mass of the RAC-P pigs and underpredicted the lean mass of the CON pigs. Only 20 to 50% of the true difference in fat-free lean mass or lipid-free soft-tissue mass between the control pigs and pigs fed RAC was predicted from equations including standard carcass measurements. The soft-tissue lipid and total carcass fat mass of RAC-P pigs was overpredicted from the carcass and live ultrasound measurements. Prediction equations including standard carcass measurements with dissected ham lean alone or with dissected loin lean reduced the residual standard deviation and magnitude of biases for the three measures of carcass leanmass. Prediction equations including the percentage of lipid of the other cut soft tissue improved residual standard deviation and reduced the magnitude of biases for total carcass fat mass and soft-tissue lipid. Prediction equations for easily obtained carcass or live ultrasound measures will only partially predict the true effect of RAC to increase carcass leanness. Accurate prediction of the carcass composition of RAC-fed pigs requires some partial dissection, chemical analysis, or alternative technologies.

To compare health and growth performance in barrows reared in all-in/all-out (AIAO) or continuous flow (CF) management systems.400 barrows.Barrows (approx 2 months old) were allotted to 4 replications (100 barrows each); barrows were housed in AIAO or CF rooms (10 pens/room), and 50 pigs/replicate received chlortetracycline (CTC, 110 mg/kg of feed). Barrows from each pen were slaughtered at 3, 4, 5, and 6 months old.Barrows in the AIAO room had greater total daily gain (TDG) and lean daily gain (LDG) than did barrows in the CF room. Addition of CTC did not improve TDG or LDG in either environment. Barrows in the AIAO room reached body weight of 104.5 kg in 169.7 days, compared with 177.3 days for barrows in the CF room. Feed-to-gain ratio was not affected by management or CTC. Lungs from barrows reared in AIAO facilities had a lower percentage of lesions than did lungs of barrows reared in CF facilities (1.74% vs 9.52%). Addition of CTC did not affect prevalence and extent of lung lesions. Extent of lung lesions was positively correlated with change in serum optical density (OD) to Mycoplasma hyopneumoniae (r = 0.35), but not with change in serum OD to Actinobacillus pleuropneumoniae. Lean growth and serum OD to M. hyopneumoniae and A. pleuropneumoniae were not correlated.Health and growth performance were better for barrows in an AIAO facility, compared with a CF facility, but addition of CTC to feed failed to enhance health or performance of barrows in either facility.

A commercial swine herd was selected for study, because pigs at slaughter repeatedly had lung lesions consistent with enzootic pneumonia and had snout lesions typical of atrophic rhinitis. Pigs born during various seasons of the year were allotted to 4 investigations and were evaluated from birth to slaughter. Individual lungs and snouts were identified and collected at the slaughter plant and later examined for gross lesions of bronchopneumonia and atrophic rhinitis, respectively. Each lesion was scored, and the following comparisons were made within investigations: prevalence and mean scores for lung lesions; prevalence and mean grades for snout lesions; correlations between lung lesion scores and growth indicators; correlations between snout lesion grades and growth indicators; and correlations between lung lesion scores and snout grade scores. Included in the growth indicators were average daily gain during the growing phase, average daily gain during the finishing phase, average daily gain during growing and finishing phases, and days to attain 104.5 kg of body weight. Prevalence of lung or snout lesions, mean values for lung lesion scores, mean values for snout lesion grades, and mean values for the various growth indicators were tested for statistical differences among the 4 investigations. Prevalence of lung lesions was highest (96%) for winter-slaughtered and lowest (81%) for autumn-slaughtered pigs. Mean scores for lung lesions were 7% (summer), 5% (autumn), 9% (winter), and 16% (spring). Prevalence of snout lesions was highest (85%) for spring-slaughtered pigs and lowest (42%) for autumn-slaughtered pigs.(ABSTRACT TRUNCATED AT 250 WORDS)

Three commercial swine herds were selected for study, because pigs at slaughter consistently had lung lesions typical of bronchopneumonia and snout lesions consistent with atrophic rhinitis. Pigs were reared in the conventional system for each herd except that they were identified at birth and weighted at various intervals. At slaughter, individual pig lungs and snout were examined for lesions of pneumonia and atrophic rhinitis, respectively. Lesions were scored and correlated with growth indicators for each pig. Included in the growth indicators were: average daily gain (growing phase), average daily gain (finishing phase), average daily gain (total), and days to reach 104.5-kg body weight. Additionally, for each pig, scores for lung lesions were correlated to grades for snout lesions. Three correlation coefficients for measurements of pigs within herd B were significant and included days to 104.5-kg body weight and grades for snout lesions, -0.15 (P less than 0.02); average daily gain (finishing) and grades for snout lesions, 0.17 (P less than 0.01); and average daily gain (total) and grades for snout lesions, 0.16 (P less than 0.01). Contrary to findings in other investigations, pigs that attained market weight at the youngest age did not have the lowest score for lung lesions, the lowest grade for snout lesions, or the least extensive or severe lesions. Combining data from all 3 herds, the mean scores for lung lesions and mean grades for snout lesions decreased significantly (P less than 0.05) as the age of pigs at slaughter increased. All other statistical correlations were not significant.(ABSTRACT TRUNCATED AT 250 WORDS)

The first 100 single-boar services of 140 boars were analyzed to determine whether the farrowing rate resulting from initial services predicted the farrowing rate of subsequent services. The data were analyzed for the influence of parity, number of matings per estrus, season of service, and interaction of these variables on farrowing rate. Sow parity influenced farrowing rate. Sows with parity greater than 8 and gilts had the lowest farrowing rates (P less than 0.01). Sows with parity 2 through 5 had the highest farrowing rates (P less than 0.01). One and 2 matings/estrus resulted in reduced farrowing rates (P less than 0.01), compared with farrowing rates of greater than 2 matings/estrus. Farrowing rate for services during the summer was lower than that for other seasons of the year (P less than 0.01). Evidence of interaction among these variables was not found. Therefore, the results of each service recorded was adjusted to the mean farrowing rate of sows with parity 2 through 5, sows mated greater than or equal to 3 times/service, and sows serviced in the spring. After these adjustments, the farrowing rates for the first 10, 20, 30, 40, and 50 services were analyzed to determine associations with farrowing rates for subsequent services through 100 farrowings. These data also were analyzed to determine whether the associations were strengthened by removal of the first 10 services from the data. The best farrowing rate association indicated that for each 1% increase in farrowing rate subsequent to the first 50 services, the farrowing rate for the second 50 services increased 0.33% (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)