Energy metabolism in young pigs as affected by establishment of new groups prior to transport.

Energy metabolism was studied in 9-week-old-pigs as affected by mixing just before transport. In each of three trials, two groups of 20 pigs (two litters of 10) were randomly assigned to one of two treatments: control and mixing. Each group was housed in one of two climatic chambers with each subgroup in one of two pens. In each trial, the two litters within the mixing treatment were mixed, just before transport, at the start of a 2-week experimental period. In the control treatment, the social structure of both litters in each trial was not altered. In both treatments, large alterations of energy partitioning from week 1 to week 2, are probably signs of recovering from transportation and/or adaptation to new feeding and housing conditions. Mixing just before transport did not change total energy metabolism but only increased nonactivity-related heat production by 3.1% for the total experimental period. Most likely, long-term performance is also not affected negatively by mixing. Animals seem to be able to change energy expenditure on activity when more energy is required for other physiological processes. This symptom of possible reallocation of energy between different vital live processes (e.g. behavior, protein turn-over) might be one of the first indications of an impaired well-being.

Effect of hemoglobin status on humoral immune response of weanling pigs differing in coping styles.

The effects of hemoglobin (Hb) status and coping style of pigs on performance and humoral immune response were studied. Twenty-four, 4-wk-old crossbred barrows were assigned to groups of three pigs based on weight and litter origin. Groups were allotted according to a 2 x 2 factorial treatment arrangement: two blood Hb concentration classes (low vs high) and two immunization procedures (control vs immunized). Immunized pigs received an antigen cocktail containing keyhole limpet hemocyanin (KLH), ovalbumin (OA), and tetanus toxoid (TT) at weaning. Additionally, pigs were stratified according to behavioral coping style in response to exposure to a stressor. During 41 d after weaning (approximate time of immunization), blood Hb concentration, ADG, and ADFI were measured weekly and serum antibody titers to KLH, OA, and TT twice weekly. Average Hb concentration differed between low and high Hb pigs (P < .001; 10.0 vs 12.0 g/dL), but this difference declined with time after weaning. Neither immunization procedure nor coping style affected Hb concentrations. In addition, ADG and ADFI were unaffected by any of the treatments. However, ADG was slightly greater in high Hb status pigs (586 vs 633 g/d) and was paralleled by a slightly greater ADFI in high Hb status pigs (812 vs 899 g/d). Antibody responses were negatively or not related to Hb status at weaning. Antibody responses (depending on isotype and antigen) were or tended to be lower in pigs with high blood Hb concentrations. Behavioral coping style strongly affected humoral immune responsiveness; enhanced or accelerated antibody responses were found in pigs that had a passive coping style.

Effectiveness of a pair-gain feeding strategy for individually fed, group-housed finishing pigs.

Crossbred barrows (n = 48) and gilts (n = 12) were used to examine the effectiveness of a pair-gain feeding strategy for individually fed, group-housed barrows. In a pair-gain feeding strategy, barrows were individually restricted to a feeding level at which their growth was similar to the mean growth of gilts with ad libitum access to feed. The purposes of this feeding strategy were to have barrows and gilts reach slaughter weight at the same time and to improve carcass traits of the barrows. At 29.8 +/- .4 kg BW, barrows were assigned to either the pair-gain or the ad libitum treatment. All pigs had free access to feed until they reached 60 kg BW. The experimental period was from 60 to 110 kg BW. The 12 group-fed gilts and 24 individually fed barrows (12 per pen) were also given free access to feed throughout the experimental period. The remaining 24 barrows (12 per pen) were put on a pair-gain feeding strategy. In the pair-gain feeding strategy, the weekly feed allowance of each barrow was based on its measured BW and computed energy conversion ratio and on the mean growth of the gilts. The barrows in the pair-gain treatment grew at the same rate as gilts. The ad libitum intake barrows grew faster (P < .05) and had a poorer energy conversion ratio for production than the barrows in the pair-gain treatment. The total energy conversion ratio, backfat thickness, and lean meat percentage were similar (P > .10) for the two treatments. In conclusion, the pair-gain feeding strategy was effective in achieving similar growth between barrows and gilts. The total energy conversion ratio and carcass traits of the barrows, however, were not improved.

Effect of hemoglobin and immunization status on energy metabolism of weanling pigs.

We investigated the effect of (Hb) and immunization status on energy metabolism of newly weaned pigs. An additional focus of the study was to determine the development of circadian rhythms as evidenced by heat production patterns. Twenty-four 4-wk-old crossbred weanling barrows were placed into groups of three based on weight and litter origin, and the groups were allotted to one of four treatments. Treatments were arranged as a 2 x 2 factorial. The factors included 1) Hb status (low vs high) and 2) immunization status (antigen vs placebo). Hemoglobin status was obtained by injecting 3-d-old barrows with 100 (low) or 200 mg (high) of Fe. At 4 wk, initial blood Hb concentrations were 6.0 mM for the low group and 7.8 mM for the high group. Energy metabolism was measured using two weekly total energy and nitrogen balance collections. Energy intake and retention were higher (P < .05) in pigs with a high Hb level. Energy metabolism was not affected (P > .10) by immunization status, and heat production was not affected (P > .10) by either Hb or immunization status. Total heat production (HTOT) increased (P < .001) daily and reflected a daily increase (P < .001) in activity (HACT) and activity-free (HCOR) heat production. An increase (P < .001) in HTOT and HACT was detected for the light period compared with the dark period over the total experimental period but a decrease (P < .001) in HCOR was detected; however, HACT for the dark period was approximately half of that measured during the light period. In conclusion, Hb status affected energy metabolism; pigs having a high Hb status had a higher energy retention. Immunization status had minimal effects on energy metabolism and heat production. Additionally, the diurnal circadian rhythm seen in older pigs had not been established by 2 wk after weaning.

Effectiveness of a zinc amino acid chelate and zinc sulfate in restoring serum and soft tissue zinc concentrations when fed to zinc-depleted pigs.

In a 36-d experiment, 32 pigs were depleted of Zn (24 d) using a soy-isolate (basal) diet (17 mg/kg of Zn) and then fed the basal diet (12 d) supplemented with 45 mg/kg of Zn from ZnSO4 (purified zinc sulfate dry powder, ZnSO4.nH2O) or from a Zn amino acid chelate (ZnAAC) to study the effectiveness of these dietary Zn sources in restoring serum and soft tissue Zn concentrations. Concurrently, nondepleted pigs were pair-fed both Zn-supplemented diets (eight pigs per diet) throughout the experiment. Serum Zn concentrations and serum alkaline phosphatase (ALP) activity of pigs fed the diets with no supplemental Zn were lower (P < .05) than those of nondepleted pigs after 7 and 14 d, respectively. After 24 d, concentrations of Zn in liver, pancreas, kidney, brain, and small intestine of Zn-depleted pigs were lower (P < .01) than those of nondepleted pigs. Except for decreased (P < .001) kidney Cu, soft tissue Cu and Fe concentrations were not affected by Zn status or Zn source. From d 24 to 36 (Zn repletion), serum and tissue Zn concentrations and serum ALP activities increased (P < .05), but the response was similar for both Zn sources in Zn-depleted and nondepleted pigs. At d 30 and 36, kidney Cu was increased (P < .01) in Zn-depleted pigs fed 45 mg/kg of Zn as either ZnSO4 or ZnAAC. Furthermore, Fe concentration was higher (P < .05) in intestinal segments of Zn-depleted and nondepleted pigs fed ZnAAC than in pigs fed ZnSO4. Accumulations of Cu in the kidney and Fe in the small intestine were affected by depletion and repletion of Zn and by dietary Zn source, respectively. In conclusion, serum and soft tissue Zn concentrations were clearly affected by Zn status: however, an effect of Zn source was not observed.

Energy metabolism in young pigs as affected by mixing.

The effect of mixing on energy metabolism was studied in 8-wk-old pigs. In each of two trials, two clusters of 20 pigs (two litters of 10 pigs) were randomly assigned to one of two treatments: control or mixing. Each cluster was housed in two pens. In each trial, after a preliminary period od 2 wk, the two litters within the mixing treatment were mixed at the start of a 2-wk experimental period. During mixing, the five heaviest pigs of each litter were put together in one pen, and the five lightest pigs of each litter were put together in the other pen. In the control treatment, the social structure of both litters in one climatic chamber was not altered. After mixing, a short-term effect on total heat production and activity-related heat production was present. Both were increased (P < .01) only during the 1st h after mixing. Only 57.3% of this increased total heat production was caused by an increased activity. However, no long-term effects of mixing on energy partitioning were present during the total experimental period. The absence of a long-term mixing effect might be caused by the optimal conditions at the moment of mixing. In the preliminary period the transposition of GE into ME increased 1.3% (P < .05), and ME for maintenance decreased 80 kJ.kg(-.75).d(-1) (P < .01) between wk 1 and 2. These large alterations in energy metabolism are probably a carry-over effect of the transportation of the pigs and (or) the changes in housing environment.

The role of feed consumption and feed efficiency in copper-stimulated growth.

Two experiments were conducted to study the role of feed intake and feed efficiency in Cu-stimulated growth of weanling pigs. In Exp. 1, 42 pigs were randomly assigned into three treatments: 1) control: ad libitum access to a corn-soybean meal-dried whey basal diet; 2) ad libitum/Cu: ad libitum access to the basal diet supplemented with 215 ppm of Cu; or 3) pair-fed/Cu: pair-fed the Cu-supplemented diet to the level of the control. Over the 14-d experiment, the ad libitum/Cu pigs had greater (P < .05) ADG and ADFI than the control pigs. The pair-fed/Cu group had an intermediate ADG. Gain:feed (GF) was not significantly affected by treatments but tended to be improved in the pair-fed/Cu pigs. Feeding copper increased (P < .05) the concentration of Cu in the serum, liver, and brain. Also, feeding Cu increased (P < .05) serum mitogenic activity and growth hormone mRNA concentrations for both feeding methods. In Exp. 2, a 2 x 2 x 2 factorial arrangement of treatments with two levels of Cu (15 vs 200 ppm), two levels of feeding (ad libitum vs restricted [85% of the ad libitum]), and two sources of Cu (Cu sulfate vs Cu lysine) was used in a 24-d experiment involving 96 pigs. Feeding copper increased (P < .05) ADG and GF. The magnitude of the Cu-stimulated growth was reduced by restricted feeding (Cu level x feeding level interaction; P < .05). The ADFI was greater (P < .05) for the pigs fed high dietary Cu only during d 1 to 6. Pigs fed Cu lysine had greater ADG and ADFI than those fed Cu sulfate (P < .05); the benefit in ADG from Cu lysine was reduced by restricted feeding (Cu source x feeding level interaction, P < .05). High dietary Cu stimulated (P < .05) serum mitogenic activity; the stimulation was greater for Cu lysine than for Cu sulfate. Feeding Cu numerically increased GH mRNA concentration. Restricted feeding reduced overall serum mitogenic activity (P < .05), but the response to high dietary Cu and Cu lysine was still evident. In summary, Cu-stimulated growth was largely dependent on a simultaneous increase in feed intake, but there were some improvements in GF. The influence of Cu on serum mitogenic activity was independent of feed intake or growth in both experiments, which indicates a direct action of Cu on the growth regulatory system.

Stimulation of growth by intravenous injection of copper in weanling pigs.

This study was conducted to examine whether Cu could exert its growth-promoting effect when injected, rather than being fed, and thus bypass the gastrointestinal tract. In two 18-d experiments, pigs were injected every 2 d with a Cu histidinate or histidine solution. Amounts of Cu injected were calculated to simulate varying absorption rates in pigs fed 250 ppm of dietary Cu. In Exp. 1, 44 pigs were randomly assigned to four groups of 11 pigs each. Pigs were injected with four levels of Cu histidinate (0, 5, 10, and 15% estimated apparent absorption coefficients based on calculated feed intake). Average daily gain responded quadratically (P < .05) to levels of Cu histidinate; maximum growth was seen in the 5% group. At d 6, serum mitogenic activity also exhibited a similar quadratic response (P < .05). In Exp. 2, estimated Cu absorptions of 0, 2, 4, 6, and 8% were tested. Forty-five pigs were randomly assigned to five groups of nine pigs each and injected as in Exp. 1. Both ADG and serum mitogenic activity displayed a quadratic response (P < .05); the maximum response was seen in the 4% group. Liver Cu content, superoxide dismutase activity, and serum Cu concentrations were linearly increased (P < .05) with increasing dosage of Cu in both Exp. 1 and 2. Also, brain Cu content linearly increased (P < .05) with increasing dosage of Cu in both Exp. 1 and 2. Also, brain Cu hormone mRNA concentrations in Exp. 2 were not significantly influenced by treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

[The effect of vitamin administration to sows during weaning on the weaning-estrus interval and on the number of live piglets in the next litter]. / De invloed van het toedienen van vitaminen aan zeugen, bij het spenen, op het interval spenen-bronst en op het aantal levend geboren biggen in de volgende worp.

The effect of injection of additional vitamins in sows during weaning on the weaning-oestrus interval and on the number of piglets born alive in the next litter was studied in 735 sows. On five commercial farms, a total of 735 sows were divided into 3 groups. The first group was injected with 10 ml of a preparation of AD3E. The second group was injected with 10 ml multivitamin. The third group was not treated. It is concluded that injection of additional vitamins did not have any effect on the weaning-oestrus interval and on the number of piglets born alive in the next litter.