Effects of temperature on the performance of finishing swine: II. Effects of a cold, diurnal temperature on average daily gain, feed intake, and feed efficiency

Forty-eight crossbred barrows and gilts weighing 84.5 +/- .33 kg were used during two 21-d trials to investigate the effects of a cold, diurnal temperature (CD; -5.0 to 8.0 degrees C) compared with a constant, thermoneutral temperature (TN; 20 degrees C) and the effects of sex (barrows vs gilts) on performance. A second objective was to determine shrinkage as a result of a 24-h fast immediately after the 21-d study of hogs commingled vs those not commingled for both environmental treatments (CD vs TN). Pigs housed in the CD chamber gained 27.2% more slowly (P less than .001; 75 vs 1.03 kg/d) than those in the TN environment and consumed 5.7% more feed (P less than .05; 3.88 vs 3.67 kg/d). The lower ADG and higher feed intake (FI) exhibited by the CD pigs resulted in poorer (P less than .05) feed efficiency (F/G; 5.33 vs 3.73, respectively). A temperature x sex interaction occurred for ADG but not for FI or F/G. Twenty-four-hour shrink for the CD pigs was 16.4% less than for the TN pigs (3.72 vs 4.45%, respectively); however, commingling did not affect shrinkage.     

Effects of temperature on the performance of finishing swine: I. Effects of a hot, diurnal temperature on average daily gain, feed intake, and feed efficiency

Ninety-six crossbred barrows and gilts weighing 90 +/- .67 kg were used during a 21-d study to determine the effects of a hot, diurnal temperature (H; 22.5 to 35 degrees C) compared with a constant, thermoneutral temperature (TN; 20 degrees C) and the effects of sex (barrows vs gilts) on performance. A secondary objective included the determination of weight loss as a result of a 24-h fast immediately after the 21-d feeding study of commingled vs not commingled hogs of both environmental treatments (TN and H). Pigs housed in the hot, diurnal temperature gained 16.3% more slowly (P less than .001;.77 vs. .92 kg/d) than those in the constant, thermoneutral environment. Feed intake (FI) for the H pigs was 10.9% less (P less than .001; 3.01 vs 3.38 kg/d) than that for the TN pigs. The H pigs gained 17.6 g/d less and consumed 43.5 g/d less feed for every C degrees above 20 degrees C; however, no differences were observed for feed efficiency (F/G; 3.86 vs 4.19 kg for the TN and H pigs, respectively). Average daily gain and feed/gain (F/G) were not affected by sex. Likewise, no significant interactions of temperature x sex were observed for ADG, FI, or F/G. Weight loss (shrinkage) during the 24-h fast was not affected by commingling; however, the H pigs lost 17.5% more weight (P less than .05) than the TN pigs (3.82 vs 3.25%, respectively).     

Liquid diets accelerate the growth of early-weaned pigs and the effects are maintained to market weight

Piglets (n = 240, 11.0+/-0.1 d old, 3.93+/-0.05 kg) were allotted to one of four treatments in a 2 x 2 factorial arrangement to examine the effects of diet physical form and nursery environment during the first 14 d after weaning on growth to market weight. During the treatment period, pigs were housed (10 pigs/ pen) in either a conventional hot nursery (30 degrees C) or a segregated-temperature nursery (cool ambient temp. of 24 degrees C, with enclosed hot-box hovers at 32 degrees C). Pigs in each environment were fed nutritionally identical diets in either liquid or dry-pellet form for 14 d. Subsequently, all pigs were fed identical dry diets and were housed in common grower-finisher facilities (penned by sex, five pigs/pen). At the end of the treatment period (d 14), pigs fed the liquid diet were 21% heavier than pigs fed the dry pellet diet (9.22 vs 7.60 kg; P < 0.001). Similarly, gain, feed intake, and gain/feed of liquid-fed pigs were 44%, 18%, and 22% greater, respectively, than observed for pigs fed the dry pellet diet. No main effect of environment was observed (P > 0.10); however, an interaction with diet physical form occurred during the early-nursery period (P < 0.01). Pigs fed the liquid diet showed better performance in the conventional nursery, whereas pigs fed the dry pellet diet were favored in the segregated-temperature nursery. No major differences in growth performance or in ultrasound carcass measurements were detected during the growing-finishing period; however, the advantage in body weight of liquid-fed pigs gained during the first 2 wk postweaning was maintained to the end of the trial (113.9 vs 110.6 kg; P < 0.05). Pigs that were fed the early-nursery diet in liquid form reached market weight (110 kg) 3.7 d sooner than the dry-fed controls (P < 0.01). Estimates of lean gain (calculated from live ultrasound data) were unaffected, suggesting that composition of growth was not altered. Collectively, these results show that liquid feeding during early life can markedly accelerate piglet growth performance and that the growth advantage is maintained to market weight, with no evidence of compensatory gain in the dry-fed control pigs.     

Acclimation to high ambient temperature in Large White and Caribbean Creole growing pigs

The effect of breed [Creole (CR) vs. Large White (LW)] on performance and physiological responses during acclimation to high ambient temperature was studied in 2 experiments involving 24 (12/breed) growing pigs each. Pigs were exposed to 24 degrees C for 10 d (d -10 to -1) and thereafter to a constant temperature of 31 degrees C for 16 d (d 1 to d 16) in Exp. 1 and for 20 d (d 1 to d 20) in Exp. 2. For both experiments, the temperature change was achieved over 4 h on d 0. The first experiment began at 105 d of age, and the average BW of CR and LW pigs was 36.6 +/- 2.5 kg and 51.7 +/- 3.0 kg, respectively. The second experiment was designed to compare both breeds at a similar BW (about 52 kg on d 0). Pigs were individually housed and given ad libitum access to feed. At 24 degrees C, ADG was lower (P < 0.01) in CR than in LW (602 vs. 913 g/d and 605 vs. 862 g/d in Exp. 1 and 2, respectively), but the ADFI was not affected by breed (190 and 221 g x d(-1) x kg(-0.60) in Exp. 1 and 2, respectively). Short-term thermoregulatory responses during the 4-h transition from 24 to 31 degrees C (d 0) were analyzed according to a linear plateau model to determine the break point temperature, above which rectal temperature (RT), cutaneous temperature (CT), and respiratory rate (RR) began to change. The CT increased linearly with temperature increase (0.22 degrees C/ degrees C) and was less (P < 0.05) in CR than in LW (by -0.3 degrees C on average). In both experiments, the break point temperature for RT was not affected by breed (27.6 degrees C on average), whereas for RR it was greater (P < 0.05) in CR than in LW (27.5 vs. 25.5 degrees C, P < 0.01). On average, ADFI declined by about 50 g x d(-1) x kg(-0.60) from d -1 to d 1 (P < 0.01), and thereafter at 31 degrees C, it gradually increased (23 g x d(-1) x kg(-0.60); P < 0.05), suggesting an acclimation to high exposure. This response was not influenced by breed. After the day that marked the beginning of the acclimation response (i.e., the threshold day), RR, CT, and RT declined over the duration of exposure to 31 degrees C (P < 0.05) in both experiments. During this period, RT and CT were less in CR than in LW pigs (39.6 vs. 39.9 degrees C and 37.9 vs. 38.2 degrees C, respectively; P < 0.05), whereas RR was not affected by breed. The threshold day at which RT began to decline was less in CR than in LW pigs (0.18 vs. 1.17 d and 0.39 vs. 0.93 d in Exp. 1 and 2, respectively; P < 0.05). In conclusion, this study suggests that short- and long-term physiological reactions during heat acclimation differed when CR and LW pigs were compared at the same age or BW.     

Hepatic corticosteroid-binding globulin (CBG) messenger RNA expression and plasma CBG concentrations in young pigs in response to heat and social stress

Plasma cortisol, porcine corticosteroid-binding globulin (pCBG), hepatic CBG expression, and other physiological and behavioral measures of stress were studied in pigs in response to elevated temperature in conjunction with establishing a social hierarchy. Twenty-four crossbred pigs were weaned at 25 d of age (three or six pigs from six sows) and housed in littermate groups at 23 +/- 2 degrees C. At 57 d of age (d 0), animals were weighed and placed under general anesthesia for collection of blood (10 mL) and liver (approximately 100 mg) samples. On d 1, three unacquainted pigs of similar BW (23 +/- 1 kg) from different litters were allotted to each of eight nursery pens within two environmentally controlled rooms (12 pigs per room). From d 1 to 7, one room was maintained at 23 +/- 2 degrees C (CON) and the other at 33 +/- 2 degrees C (HEAT). Both rooms were kept at 23 +/- 2 degrees C from d 8 to 14. Animals were videotaped for 72 h beginning on d 1 and 8 to document behavioral changes in response to room temperature. The social hierarchy of pigs within each pen was based on fight activity recorded on d 1 to 3. Blood and liver tissue were collected again on d 7 and 14. The ADG for HEAT pigs increased (P < 0.05) over d 8 to 14 compared with d 1 to 7. In contrast to CON pigs, HEAT pigs displayed increased (P < 0.01) drinking but decreased feeding and lying in contact with other pigs from d 1 to 3, and similar drinking and feeding but increased (P < 0.01) lying with contact behaviors from d 8 to 10. With the exception of subordinate pigs exhibiting less (P < 0.05) frequent standing/walking behavior than the dominant or intermediate pigs on d 1 to 3, frequency of behaviors for both recorded time periods did not differ among pigs due to social status, regardless of treatment. The concentration of plasma haptoglobin in HEAT pigs on d 7 compared with d 0 increased (467 vs. 763 mg/L; P < 0.05), whereas cortisol and pCBG decreased (274 vs. 235 nmol/L and 11.4 vs. 9.9 mg/L, respectively; P < 0.05) as a result of treatment. The free cortisol index (total cortisol/pCBG) was greater (P < 0.05) in HEAT pigs on d 14 than on d 0 or 7. Hepatic CBG mRNA level was not affected by treatment. On d 14, HEAT pigs had plasma cortisol, pCBG, and haptoglobin concentrations similar to those of CON pigs. These results indicate that measured behavioral and physiological responses were not related to social status, and decreased circulating levels of cortisol and pCBG in pigs following a 7-d exposure to elevated temperature may not be determined by hepatic CBG mRNA expression.     

Effects of dietary ingredients on manure characteristics and odorous emissions from swine

Two feeding studies were conducted to examine the impact of dietary inclusion of specific feed ingredients on manure characteristics and manure odor. In one study, 72 finishing pigs were used to evaluate the effects of distillers dried grains with solubles (DDGS) on pig performance, manure characteristics, and odorous emissions. Three diets containing 0, 5, and 10% DDGS were fed during six 4-wk feeding periods. Week 1 served as a dietary adjustment period. Animals were housed in two feeding rooms (six pigs/room) with one treatment/room. A new group of animals (average initial BW = 85.8 kg) was used for each feeding period. Diets were replicated four times. Rooms were equipped with individual shallow manure storage pits that were cleaned once weekly (d 7). On d 4 and 7 of each week, manure pit samples, for chemical analyses, and air samples, for olfactometry analysis, were collected from each room. Odor dilution threshold was greater on d 7 than on d 4 of manure storage across all treatments (P < 0.01). No treatment differences in manure composition were noted. In the second study, weaned pigs (approximately 5 wk old) were fed isonitrogenous diets containing 0, 1.5, or 3% bloodmeal. Pigs were housed by diet (three pigs/diet) in one of four individual feeding rooms. A new group of pigs was used for each of the two, 4-wk feeding periods. During period 1, the 3% bloodmeal diet was fed in two of the four rooms; the 0% bloodmeal diet was fed in two rooms during period 2. Manure samples, for chemical analyses, and air samples, for olfactometry analysis, were collected 2 d per week (d 4 and d 6) from each room during wk 2 through 4. No significant treatment differences were observed for odor dilution threshold (P = 0.30). Longer manure storage time, 6 d vs 4 d, resulted in a larger odor dilution ratio (P < 0.01). Manure composition was unaltered by storage time. Results suggest that odor intensifies during storage.     

The effects of thermal environment and spray-dried plasma on the acute-phase response of pigs challenged with lipopolysaccharide

Forty barrows (TR4 x C22) were weaned at 17 d of age (BW = 6.27 +/- 0.30 kg), housed (two pigs/pen) in a thermal-neutral environment (TN; constant 26.7 degrees C), and fed diets with or without 7% (as-fed basis) spray-dried plasma (SDP). On d 7, one pig/ pen was moved into a cold environment (CE; constant 15.6 degrees C). Pigs were fitted with jugular catheters on d 11. On d 12, 16 pigs per environment (eight pigs per dietary treatment) were challenged i.v. with 75 microg of lipopolysaccharide (LPS)/kg of BW. Blood samples were collected over a 4.5-h period. Pigs were then killed and tissue samples were harvested for messenger RNA (mRNA) analysis. From d 0 to 7, pigs fed SDP diets had a lower gain:feed ratio (G/F) than pigs fed no SDP (533 +/- 14 vs. 585 +/- 17 g/kg; P < 0.03). Pigs housed in the CE consumed more feed and had a lower G/F than pigs housed in TN from d 7 to 11 (P < 0.001). There were no environment x diet interactions from d 7 to 11 (P > 0.78). Baseline concentrations of serum ACTH and cortisol were lower in the TN pigs than in the CE pigs (P < 0.001). Pigs fed diets without SDP had lower serum cortisol concentrations over the 4.5-h period than pigs fed SDP (time x diet, P < 0.001). Serum concentrations of tumor necrosis factor-alpha (TNF-alpha) were highest for pigs consuming SDP in the CE, whereas there were no differences among the other treatments (time x diet x environment, P < 0.02). Pigs housed in the CE had higher serum interleukin-1beta (IL-1beta) (P < 0.001) and interleukin-6 (IL-6; P < 0.001) than TN pigs. Pigs fed SDP also had slightly higher serum IL-1beta concentrations (P < 0.10) and higher (P < 0.001) IL-6 concentrations than pigs fed no SDP. Pigs fed SDP had 9% lower liver and 13% lower thymus mRNA expression of tumor necrosis factor-alpha (TNF-alpha) than pigs that consumed no SDP (P < 0.06). Liver IL-1beta, IL-6, and LPS-binding protein mRNA were higher in the CE than in the TN (P < 0.03, P < 0.001, and P < 0.05; respectively). In addition, spleen TNF-alpha (P < 0.03) and IL-6 (P < 0.01) mRNA levels were higher in the CE than in the TN. Pigs consuming SDP and challenged with LPS responded with elevated serum concentrations of cortisol and cytokines compared with pigs fed diets with no SDP. Housing pigs in a CE increased the baseline concentrations of ACTH and cortisol, and when coupled with an LPS challenge, resulted in elevated serum and tissue mRNA levels of cytokines. Cold stress and feeding SDP during a LPS challenge may result in increased stress and immune responses in young pigs.     

Direct and correlated responses to two-stage selection for ovulation rate and number of fully formed pigs at birth in swine

Our objectives were to estimate responses and genetic parameters for ovulation rate, number of fully formed pigs at birth, and other production traits following two-stage selection for increased ovulation rate and number of fully formed pigs. Eight generations of selection were practiced in each of two lines. One selection line was derived from a line that previously selected eight generations for an index to increase ovulation rate and embryonic survival (the IOL pigs). The other selection line was derived from the unselected control line of the index selection experiment (the COL pigs). The control line (C) was continued with random selection. Due to previous selection, Line IOL had greater ovulation rate (4.24 +/- 0.38 and 4.14 +/- 0.29 ova) and litter size (1.97 +/- 0.39 and 1.06 +/- 0.38 pigs) at Generation 0 of two-stage selection than did Lines COL and C. In Stage 1, all gilts from 50% of the largest litters were retained. Approximately 50% of them were selected for ovulation rate in Stage 2. Gilts selected for ovulation rate were mated to boars selected from the upper one-third of the litters for litter size. At Generations 7 and 8, differences in mean EBV for ovulation rate and litter size between Lines IOL and C were 6.20 +/- 0.29 ova and 4.66 +/- 0.38 pigs; differences between Lines COL and C were 2.26 +/- 0.29 ova and 2.79 +/- 0.39 pigs; and differences between Lines IOL and COL were 3.94 +/- 0.26 ova and 1.86 +/- 0.39 pigs. Regressions of line mean EBV on generation number were 0.27 +/- 0.07 ova and 0.35 +/- 0.06 pigs in Line IOL; 0.30 +/- 0.06 ova and 0.29 +/- 0.05 pigs in Line COL; and 0.01 +/- 0.07 ova and 0.02 +/- 0.05 pigs in Line C. Correlated responses were decreased age at puberty and increased number of pigs born alive, number of mummified pigs, prenatal loss, and individual and litter birth weight. Two-stage selection for ovulation rate and number of pigs per litter is a promising procedure to improve litter size in swine.     

Effects of double stocking and weighing frequency on pig performance in wean-to-finish production systems

Two studies were carried out in different wean-to-finish barns to determine the effects of double stocking on pig growth performance. In Study 1, pigs (n = 1,560) were used in a randomized complete block design with a 2 x 2 factorial arrangement of treatments: initial stocking treatment (Single [52 pigs/pen] vs Double [104 pigs/pen] stocked for 10 wk after weaning) and weighing frequency (High [12 times during the study] vs Low [3 times]) on pig performance from weaning (5.9+/-0.01 kg BW; 17 d of age) to harvest (114+/-0.67 kg BW). Floor and feeder space per pig were 0.650 m2 and 4 cm and 0.325 m2 and 2 cm for the single- and double-stocked treatments, respectively. In Study 2, pigs (n = 1,458) were used in a randomized complete block design to evaluate two initial stocking treatments (Single [27 pigs] vs Double [54 pigs] stocked for 10 wk after weaning) on pig performance from weaning (4.8+/-0.01 kg BW; 15 d of age) to harvest (24 wk after weaning). Floor and feeder space per pig were 0.640 m2 and 3.4 cm and 0.320 m2 and 1.7 cm for single- and double-stocked pens, respectively. In both studies, double-stocked pigs were split at the end of wk 10 into two equal-sized groups of similar mean BW and CV of BW, and one group was moved to a different pen in the same building. In Study 1, performance was not affected (P > 0.10) by frequency of weighing. For the first 10 wk after weaning, the Double compared to the Single treatment had lower ADG (7.7 and 7.9%, for Studies 1 and 2, respectively; P < 0.001) and lighter pigs at wk 10 (6.8 and 7.3%, respectively; P < 0.001). During the first 10 wk in Study 1, Double compared to the Single pigs had lower ADFI (7%; P < 0.001) but similar gain:feed (P > 0.10). From wk 11 to harvest, pigs on Double and Single treatments had similar (P > 0.10) ADG in both studies and, in Study 1, ADFI was unaffected by initial stocking treatment, but double-stocked pigs had greater gain:feed (4%, P < 0.01). Double-stocked pigs required an additional 2 d to reach a fixed harvest BW (P < 0.05) in Study 1 and were lighter (4%; P < 0.05) at 24 wk after weaning in Study 2. Carcass measures were similar (P > 0.10) for double- and single-stocked pigs. Double-stocked pigs that were moved at the end of 10 wk had growth performance similar (P > 0.10) to those that remained in the original pen. In summary, double stocking reduced growth rate to 10 wk after weaning but subsequently had no effect on growth rate and improved feed efficiency.     

Effects of temperature stress on growth performance and bacon quality in grow-finish pigs housed at two densities

Managing stressors is essential for optimizing pig growth performance. To determine the effects of temperature and space allocation on growth performance and carcass characteristics, pigs were housed within their thermoneutral zone, at 23.9 degrees C, or above their thermoneutral zone, at 32.2 degrees C, and were provided either 0.66 or 0.93 m(2)/pig for the final 35 d of the grow-finish period. Individual BW were recorded on d 1, 10, 20, and 30. At slaughter, carcass measurements and samples of backfat and belly fat were collected. Final BW was decreased (P < or = 0.05) from 113 to 103 kg for pigs housed at 32.2 degrees C. The ADG was reduced (P < 0.05) for pigs housed at 32.2 degrees C (0.89 vs. 0.54 kg/d), as was G:F (0.28 vs. 0.24). Housing at 0.66 m(2)/pig resulted in pigs that were lighter (P < or = 0.05), at 106 compared with 110 kg, as a result of decreased (P < or = 0.05) ADG (0.78 to 0.65 kg/d) and decreased (P < or = 0.05) G:F (0.275 to 0.255) compared with pigs housed at 0.93 m(2)/pig. Pigs housed at a greater spatial allocation had elevated (P < or = 0.05) ADFI. The interaction of housing at 32.2 degrees C and decreasing spatial allocation increased (P < or = 0.05) the adipose iodine value from 66.8 to 70.4, decreased (P < or = 0.05) the saturated:unsaturated fatty acids ratio from 0.59 to 0.56, and increased (P < or = 0.05) the n-6:n-3 from 23.56 to 25.27. Decreased spatial allocation resulted in decreased (P < or = 0.05) belly weights. Although increased temperature did not affect belly weight, the 32.2 degrees C pigs had decreased (P < or = 0.05) raw and cooked slice weights, increased (P < or = 0.05) percentage lean of bacon, increased (P < or = 0.05) lean:fat ratio of bacon slices, increased (P < or = 0.05) raw slice scores, and increased (P < or = 0.05) quantity of collagen in belly fat. Some of these changes may have resulted from changes in lipid metabolism. Increasing spatial allocation in the 32.2 degrees C pigs decreased fatty acid synthase (P = 0.03) and stearoyl-CoA desaturase- 1 (P = 0.08) mRNA expression in adipose tissue. The results from this study demonstrated decreased growth, carcass lipid quality, and bacon quality in pigs housed at temperatures above the thermoneutral zone; however, increasing the spatial allocation for housing may be a means to ameliorate the negative effects of temperature stress.     

A modified reduced nocturnal temperature regimen for early-weaned pigs

A four-trial experiment utilizing 3- to 4-wk-old newly weaned pigs was conducted to evaluate the effect of a modified reduced nocturnal (MRNT) nursery temperature regimen on weaned pig and subsequent grower-finisher performance. Nursery treatments were 1) a control temperature (CT) regimen of 30 degrees C constant air temperature lowered 2 degrees C/wk and 2) a regimen beginning 1 wk after weaning in which the temperature from 1900 to 0700 was lowered 6 degrees C from CT. Weaned pigs gained faster (P less than .01) in the MRNT treatment than in the CT treatment, with gains in Trials 1, 2, 3 and 4 being .39 vs .37, .28 vs .27, .38 vs .37 and .39 vs .36 kg/d, respectively. This improvement in gain was due to an increase (P less than .005) in feed intake for the same periods (.60 vs .58; .48 vs .42; .59 vs .58; .63 vs .58 kg/d). There was no difference in feed conversion (P greater than .1). There was no effect (P greater than .1) of MRNT vs CT on subsequent performance to slaughter weight for average daily gain (.69 vs .69 kg/d), average daily feed (2.22 vs 2.23 kg/d) or gain/feed (.31 vs .31). These results support the conclusions that weaned pigs eat more feed and gain faster with a reduced nocturnal temperature scheme and that there are no carry-over effects during the growing-finishing phase.     

Fluctuating ambient temperature for weaned pigs: effects on performance and immunological and endocrinological functions

Following weaning at 3 wk of age, crossbred barrows and gilts were housed in temperature-controlled rooms for a 5-d adjustment period at 35 degrees C, then assigned to receive constant ambient temperature (CT) or fluctuating ambient temperature (FT) treatment for the nursery phase of the experiment. Pigs in FT received 12 h at 35 degrees C and 12 h at 15 degrees C daily for the initial 2 wk of the experiment, then 12 h at 29 degrees C and 12 h at 9 degrees C daily for the final 2 wk. Pigs in CT received 35 degrees C and 29 degrees C continuously for the first and final 2 wk, respectively. Weekly growth performance, feed intake and feed-conversion efficiency were not affected by treatment. Plasma glucose, serum cortisol, monocyte phagocytic function and antibody response to a commercial E. coli bacterin were similar in pigs exposed to CT and FT treatments. Concentrations of insulin in serum were similar between treatments at 0, 1 and 3 wk but were increased for pigs in FT at 2 (P less than .05) and 4 wk (P less than .01). Numbers of lymphocytes, band neutrophils and monocytes in pigs were not influenced by ambient temperature treatment. However, numbers of mature neutrophils for pigs in FT were increased (P less than .05) at 1 and 3 wk of treatment. Eosinophils were also elevated in FT pigs at 4 wk of treatment. Pairs of littermate pigs that had been given CT and FT treatments were selected randomly to continue on the finishing phase of the experiment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cold housing effects on growth and nutrient demand of young horses

Housing temperature effects on growth, feed utilization and feed digestion of 12, 7-mo-old Standardbred colts were evaluated for 22 wk beginning in late November. Colts were assigned to one of two treatments: housed in a barn heated at 10 degrees C (warm) or housed in a barn with no external heat supply (cold). All horses were allowed outdoors for 4 h daily. Mean temperatures of the warm and cold barn from November to April were 10.9 +/- .66 and -5.2 +/- 1.72 degrees C, respectively. Hair coat weight of cold-housed colts was 1.4- to twofold (P less than .05) that of warm-housed colts from December through April but declined for both groups from fall to spring. All colts were fed a pelleted diet to meet National Research Council (1989) energy guidelines for moderate gain (.65 kg/d). Warm-housed colts gained weight 29% more rapidly (P less than .01) than cold-housed colts (.67 vs .52 kg/d). Skeletal growth, measured by cannon bone circumference, wither and croup height, was not affected by housing temperature. Nutrient digestion by both groups of colts was compared to that of mature, warm-housed ponies. Ponies had longer (P less than .05) digestive tract retention times and higher digestibilities for every nutrient than the young horses did. Although retention times by all colts were similar, cold-housed colts digested more ADF and less phosphorus (P) than did warm-housed colts (P less than .05). Over time, digestibilities of DM, NDF and P declined (P less than .05) for colts but not for ponies. Maintenance energy needs were estimated at 34.6 kcal/kg BW for cold-housed colts vs 26.3 kcal/kg BW for warm-housed colts. Young horses need 1.3% more maintenance energy per Celsius degree decrease in temperature below 0 degree C. To sustain a constant moderate gain, daily DE intake needs to be increased .7% per Celsius degree decrease in ambient temperature below 0 degree C.     

Effect of nipple drinker water flow rate and season on performance of lactating swine.

A cooperative study involving six experiment stations and 236 crossbred litters was conducted to determine the effect of nominal nipple drinker water flows of 700 mL/min and 70 mL/min (actual = 701 and 76 mL/min, respectively) during winter (November through February; 124 litters) and summer (June through August; 112 litters) seasons on performance of lactating sows and their litters. Within a season, sows were paired according to expected farrowing date and assigned at random to crates. Water flow rate treatments were assigned at random to sows within pairs. Sows were housed in farrowing crates from d 109 of gestation until either d 21 (two stations) or d 28 of lactation (four stations). Within 24 h after farrowing, litters were adjusted to contain 8 to 12 piglets. Sow feed intake (SFI) and litter weight (LW) were recorded weekly. Sow weights were recorded at d 109 of gestation, d 0, and d 21 of lactation. Sows lactating beyond 21 d were also weighed on d 28. Analysis of covariance was applied to sow weight change, average daily SFI, and LW data where litter size after crossfostering was the covariate. Average ambient temperature 30 cm above the floor at 0830 and 1600 was 24.6 +/- 0.15 degrees C and 29.4 +/- 0.14 degrees C, respectively, during summer and 20.7 +/-0.13 degrees C and 21.8 +/- 0.11 degrees C during winter trials. Restricted drinker water flow rate decreased SFI (P < 0.01; 4.59 vs. 3.94 kg/d, respectively, for 700 and 70 mL/min) and increased BW loss (P < 0.01; 0.56 vs 0.89 kg/d, respectively for 700 and 70 mL/min) but did not affect litter size (P > 0.87) or LW (P > 0.89) during the first 21 d of lactation. During d 22 to 28, the 70 mL/min flow decreased SFI (P < 0.01; 5.02 vs. 4.47 kg/d respectively, for 700 and 70 mL/min). Over the 21-d lactation period, the 70 mL/min treatment depressed (P < 0.01) SFI more during the winter (5.12 vs. 4.24 kg/d for 700 and 70 mL/ min, respectively) than during the summer (4.05 vs 3.65 kg/d for 700 and 70 mL/min, respectively). Season affected SFI (P < 0.01; 4.68 vs. 3.85 kg/d, respectively, for winter and summer), sow weight loss (P < 0.001; 0.46 vs 0.83 kg/d, respectively, for winter and summer), and LW at 21 d (P < 0.05; 52.8 vs. 49.6 kg, respectively, for winter and summer) but not (P > 0.96) the number of pigs per litter. Results of this study suggest that ample access to drinking water and controlling ambient temperature during summer months are essential for sow and litter performance.     

Efficacy of dietary selenium sources on growth and carcass characteristics of growing-finishing pigs fed diets containing high endogenous selenium

A study was conducted to determine the efficacy of organic (Se-yeast, SelenoSource AF, Diamond V Mills Inc., Cedar Rapids, IA) and inorganic sources of Se on growth performance, tissue Se accretion, and carcass characteristics of growing-finishing pigs fed diets with high endogenous Se content. A total of 180 pigs at 34.4 +/- 0.06 kg of BW were allotted to 1 of 5 dietary treatments: a negative control without added Se (NC); 3 treatment diets with 0.1, 0.2, or 0.3 mg/kg of added Se from an organic source; and a diet with 0.3 mg/kg of added Se as sodium selenite. Each treatment had 6 pens, with 6 pigs per pen-replicate. Experimental diets were changed twice at 66.1 +/- 0.5 kg and 99.0 +/- 0.9 kg of BW, and were fed until the pigs reached market weight. Growth performance was measured at the end of each phase. Upon reaching 129.9 +/- 1.4 kg of BW, the pigs were transported to a local abattoir (Seaboard Foods, Guymon, OK), where carcass, loin, and liver samples were obtained. Hair and blood samples were obtained at the beginning and end of the study for Se analysis. Growth performance did not differ (P > 0.05) among treatments. Percent drip loss of the NC pigs was greater (2.41 vs. 1.75, P = 0.011) compared with pigs supplemented with Se. Pigs fed diets with added Se had greater Se concentrations in the liver (0.397 vs. 0.323 ppm, P = 0.015), loin (0.236 vs. 0.132 ppm, P < 0.001), serum (0.087 vs. 0.062 ppm, P = 0.047), and hair (0.377 vs. 0.247 ppm, P = 0.003) compared with the NC pigs. Percentage drip loss was linearly reduced [percent drip loss = 2.305 - (2.398 x Se), r2 = 0.29, P = 0.007] as dietary organic Se concentration increased. The Se concentration (ppm) in the liver [liver Se = 0.323 + (0.291 x Se), r2 = 0.33, P = 0.003], loin [loin Se = 0.122 + (0.511 x Se), r2 = 0.57, P < 0.001], serum [serum Se = 0.060 + (0.113 x Se), r2 = 0.33, P = 0.004] and hair [hair Se = 0.237 + (0.638 x Se), r2 = 0.56, P < 0.001] increased linearly as dietary organic Se concentration increased. Slope ratio analysis indicated that the relative bioavailability of organic Se for percent drip loss and loin and hair Se response was 306, 192, and 197% of that for inorganic Se, respectively. The results of the study show a potential advantage of organic Se supplementation in reducing drip loss even when the basal diet contains an endogenously high Se concentration of 0.181 ppm.     

Impact of early postweaning growth rate as affected by diet complexity and space allocation on subsequent growth performance of pigs in a wean-to-finish production system

The objective was to evaluate the effect of restricted early postweaning growth rate due to diet complexity, pen space, or both on subsequent growth to market in a wean-to-finish system. Pigs (n = 1,728) were used in a randomized block design with a 2 x 2 factorial arrangement of treatments: 1) diet complexity (Complex vs Simple) and 2) space allocation (Unrestricted vs Restricted). Treatments were imposed for the first 8 wk after weaning (period 1) and growth was measured from weaning (5.0 +/- 0.01 kg body weight; 15 d of age) to the end of wk 23 postweaning. The Simple diet was based on corn-soybean meal with minimal inclusion of milk products, processed cereals, and animal protein-based ingredients compared to the Complex diet. Floor and feeder-trough spaces were 0.63 m2 and 4 cm and 0.21 m2 and 2 cm per pig for Unrestricted and Restricted space treatments, respectively. From the end of wk 8 to end of wk 23 (period 2), pigs on all treatments had the same floor and feeder spaces and were fed common diets. There was no interaction (P > 0.05) between diet and space treatments. In period 1, Simple diets resulted in similar average daily feed intake (ADFI; 639 vs 650 +/- 5.4 g; P > 0.05), but lower average daily gain (ADG; 408 vs 424 +/- 3.8 g; P < 0.01) and gain:feed ratio (0.64 vs 0.65 +/- 0.002; P < 0.001), and lighter body weight (2.8%; P < 0.01) compared to the Complex diets. In period 2, growth was not affected (P > 0.05) by previous diet complexity, and pig body weight was similar (114.4 vs 114.4 +/- 0.37 kg, P > 0.05) at the end of wk 23. In period 1, pigs with Restricted space had lower ADG (398 vs 434 +/- 3.8 g; P < 0.001), ADFI (621 vs 668 +/- 5.4 g; P < 0.001), and gain:feed ratio (0.64 vs 0.65 +/- 0.002; P < 0.01), and were lighter at the end of wk 8 (6.5%; P < 0.001) than those with Unrestricted space. However, in period 2, pigs with Restricted space had higher (P < 0.01) ADG (3%), ADFI (2%), and gain:feed ratio (3%) than those with Unrestricted space, and body weight was similar (114.5 vs 114.3 +/- 0.37 kg; P > 0.05) at end of wk 23. Carcass backfat and loin-eye depth at market body weight were influenced by neither diet nor space treatment. Using a simple diet program and restricted space allowance immediately postweaning resulted in a lower early growth rate, but had no impact on pig body weight or carcass measures at market.     

Effects of pig age at market weight and magnesium supplementation through drinking water on pork quality

Thirty-two halothane-negative pigs (109 +/- 0.6 kg of BW) were used to determine the effect of pig age at marketing (and thus growth rate), and magnesium supplementation through drinking water, on pork quality. Two initial groups of 50 pigs that differed by 30 +/- 2 d of age were fed diets to meet or exceed nutrient requirements beginning at 28 kg of BW. Sixteen average, representative pigs were selected from each group to represent older, slow-growing pigs and younger, fast-growing pigs. For the duration of the study, pigs were individually penned, provided 2.7 kg of feed (0.12% Mg) daily, and allowed free access to water. After 7 d of adjustment, pigs were blocked by sex and BW and allotted to 0 or 900 mg of supplemental Mg/L as MgSO4 in drinking water for 2 d before slaughter. All 32 pigs were then transported (110 km) to a commercial abattoir on the same day and slaughtered 2.5 h after arrival. Longissimus and semimembranosus (SM) chops were packaged and stored to simulate display storage for fluid loss and Minolta color determinations at 0, 2, 4, 6, and 8 d. Two remaining sections of the LM were vacuum-packaged and stored at 4 degrees C for 25 or 50 d. Fast- (younger) and slow- (older) growing pigs differed by 27 +/- 0.3 d of age (153 and 180 +/- 0.3 d; P < 0.001) at similar BW (108 and 110 +/- 0.6 kg of BW; P = 0.13). Supplementation of Mg tended to increase plasma Mg concentration (24.1 vs. 21.8 +/- 0.8 ppm; P = 0.06) but did not affect Mg concentration in LM or SM. Fluid loss of displayed LM or SM, and purge loss, color, and oxidation of vacuum-packaged LM or SM were not affected by age or Mg (P > 0.10). Surface exudate of the SM from older pigs was lower than that of younger pigs (61 vs. 74 +/- 6 mg; P = 0.05) but was not different for the LM (P = 0.22). The LM from older pigs displayed for 4 and 8 d; P < 0.05) were less yellow (lower b*) than younger pigs. The SM from older pigs had lower lightness (L*) initially (47.9 vs. 49.5 +/- 0.4) and after 2 d (49.7 vs. 51.1 +/- 0.4), 6 d (52.1 vs. 53.7 +/- 0.4) and 8 d (54.5 vs. 55.9 +/- 0.4) of display storage. Younger pigs had greater oxidation of the LM than older pigs on d 8 of display (P < 0.01), and Mg decreased oxidation on d 8 within younger pigs (P < 0.05). Pork quality was improved in older pigs as indicated by less exudate, reduced yellowness of the LM, reduced paleness of the SM, and reduced oxidation of the LM. However, Mg supplementation through the water for 2 d did not affect pork quality of either older, slower growing pigs or younger, faster growing pigs.     

Behavior of dairy calves after a low dose of bacterial endotoxin

The aim of this experiment was to better describe early behavioral responses of calves to illness to help improve early detection. We examined the behavior of calves after injections of very low doses of bacterial lipopolysaccharide (LPS). Fifteen dairy calves of 2 ages (3 and 20 wk), housed in individual pens and fed milk and concentrates with free access to hay and water, were injected i.v. with 1 of 2 low doses (0.025 or 0.05 microg/kg of BW) of LPS before feed delivery with saline injections as a control using a crossover design. Fifteen calves showed an increased body temperature (>39.5 degrees C) lasting 2 to 8 h, with a maximum temperature of 40.59 +/- 0.52 degrees C attained 4.62 +/- 0.96 h after the LPS injection. Video recordings were used to measure durations of behaviors during a 4-h period when body temperatures were elevated. We found a decreased duration of rumination (LPS vs. saline 6.42 +/- 3.69 min vs. 24.57 +/- 6.64 min; P = 0.001) and hay eating (23.11 +/- 6.93 min vs. 31.52 +/- 7.54 min; P = 0.04), a decreased frequency of self-grooming (13.47 +/- 1.75 vs. 24.07 +/- 3.12; P = 0.008), and an increased duration of lying inactive (132.63 +/- 10.60 min vs. 104.39 +/- 12.63 min; P = 0.02). There was an increased bout frequency (P = 0.002) and mean bout duration (P = 0.005) of standing inactive. Changes in these behaviors may indicate the beginning of illness. Time spent lying down and amount of concentrate and milk consumed were not affected. There were no differences between the 2 doses and no interactions between LPS and the age of the calves. Very low doses of LPS seem promising to understand early development of sickness behaviors in dairy calves. However, the short duration of the effect and differences between calves in sensitivity to LPS must be considered as limitations to the effectiveness of this model.     

Comparative effects of level of dietary fiber and sanitary conditions on the growth and health of weanling pigs

There are conflicting results on the growth and health of weanling pigs (Sus scrofa) fed high-fiber diets, and responses may differ according to sanitary conditions. This study was conducted to explore the growth, health, and fecal microbiota of weanling pigs fed either low- or high-fiber diets in 2 different sanitary conditions. Forty-eight pigs weaned at 28 d of age were individually housed in "good" (clean) or "poor" (unclean) sanitary conditions. During 2 consecutive phases, pigs were fed 2 diets containing a low (control) or high level of fiber: 121 or 169 g/kg total dietary fiber (TDF) for Phase I and 146 or 217 g/kg for Phase II, which lasted 15 and 20 d, respectively. This led to 4 experimental treatments in Phase I in a 2 × 2 factorial arrangement (2 sanitary conditions × 2 diets) and 8 experimental treatments in Phase II in a 2 × 2 × 2 factorial arrangement (2 sanitary conditions × 2 diets in Phase I × 2 diets in Phase II). The poor sanitary conditions led to a reduced G:F (0.617 vs. 0.680 for poor and good sanitary conditions, respectively; P = 0.01) over the entire experimental period. The number of pigs with diarrhea in Phase I tended to be greater in the poor sanitary conditions with the high-fiber diet than the control diet (7 vs. 3 pigs, P = 0.07). Enterococcus was prominent in feces of these diarrheic pigs. At 5 wk after weaning, compared with good sanitary conditions, the fecal microbiota of pigs housed in poor sanitary conditions was characterized by more Lactobacillus (9.24 vs. 8.34 log cfu/g, P < 0.001), more Enterobacteria (6.69 vs. 5.58 log cfu/g, P < 0.001), and less anaerobic sulfite bacteria (3.72 vs. 5.87 log cfu/g; P < 0.001). The feces of pigs in poor sanitary conditions contained more total VFA and proportionally more butyrate (9.7 vs. 5.7% for poor and good conditions, respectively, independently of dietary treatment, P < 0.001). At 5 wk after weaning, feces of pigs fed the high-fiber diet during Phase II contained less Enterococcus bacteria than pigs fed the control diet (4.06 vs. 4.56 log cfu/g; P = 0.05), and more total VFA with a decreased proportion of branched-chain fatty acids (5.0 vs. 6.1%; P = 0.006). To conclude, feeding pigs a high-fiber diet in the immediate period after weaning is probably an additional risk factor for slower BW gain, especially in poor sanitary conditions.     

Effectiveness of an experimental consensus phytase in improving dietary phytate-phosphorus utilization by weanling pigs

Consensus phytase is a new biosynthetic, heat-stable enzyme derived from the sequences of multiple homologous phytases. Two experiments were conducted to determine its effectiveness, relative to inorganic P and a mutant enzyme of Escherichia coli phytase (Mutant-EP), in improving dietary phytate-P availability to pigs. In Exp. 1, 36 pigs (3 wk old, 7.00 +/- 0.24 kg of BW) were fed a low-P corn-soybean meal basal diet plus consensus phytase at 0, 250, 500, 750, 1,000, or 1,250 U/kg of feed for 5 wk. Plasma inorganic P concentration, plasma alkaline phosphatase activity, bone strength, and overall ADG and gain:feed ratio of pigs were improved (P < 0.05) by consensus phytase in both linear (R2 = 0.20 to 0.70) and quadratic (R2 = 0.30 to 0.70) dose-dependent fashions. In Exp. 2, 36 pigs (4 wk old, 9.61 +/- 0.52 kg BW) were fed the basal diet + inorganic P at 0.1 or 0.2%, consensus phytase at 750 or 450 U/kg of feed, Mutant-EP at 450 U/kg of feed, or 225 U consensus + 225 U Mutant-EP/kg of feed. Pigs fed 750 U of consensus phytase or 450 U of Mutant-EP/kg feed had plasma inorganic concentrations and bone strength that fell between those of pigs fed 0.1 or 0.2% inorganic P. These two measures were 16 to 29% lower (P < 0.05) in pigs fed 450 U of consensus phytase/kg of feed than those of pigs fed 0.2% inorganic P. Plasma inorganic P concentrations were 14 to 29% higher (P < 0.05) in pigs fed Mutant-EP vs. consensus phytase at 450 U/kg at wk 2 and 3. In conclusion, the experimental consensus phytase effectively releases phytate P from the corn-soy diet for weanling pigs. The inorganic P equivalent of 750 U of consensus phytase/kg of feed may fall between 0.1 and 0.2%, but this requires further determination.