The effect of different postweaning altrenogest treatments of primiparous sows on follicular development, pregnancy rates, and litter sizes

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This study investigated follicular development during and after postweaning altrenogest treatment of primiparous sows in relation to subsequent reproductive performance. Primiparous sows (n = 259) were randomly assigned at weaning (d 0) to 1 of 4 groups: control (no altrenogest, n = 71), RU4 (20 mg of altrenogest from d −1 to 2, n = 62), RU8 (20 mg of altrenogest from d −1 to 6, n = 65), or RU15 (20 mg of altrenogest from d −1 to 13, n = 61). Average follicular size (measured by ultrasound) increased during altrenogest treatment and resulted in larger follicles at the start of the follicular phase for RU4, RU8, and RU15 compared with controls (5.3, 5.5, 5.1, and 3.4 mm, respectively). Farrowing rate was greater in RU15 (95%) than in RU8 (76%). The RU15 group also had more piglets (2 to 3 more piglets total born and born alive; than the other treatment groups. Follicular development at weaning clearly affected reproductive performance. At weaning, average follicular size: small (<3.5 mm), medium (3.5 to 4.5 mm), or large (≥4.5 mm), was associated with farrowing rates of 86, 78, and 48%, respectively. Sows with large follicles at weaning had low farrowing rates (71%) in RU4, very low farrowing rates (22%) in RU8, but normal farrowing rates in RU15 (83%). In conclusion, this study showed that 15 d of postweaning altrenogest treatment of primiparous sows may allow follicle turnover in sows that had large follicles at weaning and that this was associated with an improved reproductive performance. It also showed that shorter treatment with altrenogest (4 or 8 d) is beneficial for sows with small follicles at weaning, but is not recommendable for sows with large follicles at weaning.

For more information the full article can be found at http://jas.fass.org/

Head-only followed by cardiac arrest electrical stunning is an effective alternative to head-only electrical stunning in pigs

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Many small slaughter facilities use head-only electrical stunning to render swine unconscious and insensible to pain before slaughter. Head only electrical stunning is a reversible procedure that is optimally effective for approximately 15 s after stun completion. In many small North American slaughter plants, the authors have observed hoist speeds that are too slow to achieve a short enough stun-to-bleed interval to maintain insensibility through exsanguination. Unlike many European plants, there is no separate high speed hoist for pigs and exsanguination on the floor is not condoned. As a result, a 2-stage stunning method was proposed where head-only stunning for 3 s was immediately followed by application of the same stunning wand to the cardiac region of the animal for 3 s while lying in lateral recumbancy. A paired-comparison study was conducted on 89 pigs in a small slaughter facility to compare the head-only method applied for 6 s with the head/heart method. The objective was to evaluate signs of return to sensibility, stun-to-bleed time, blood lactate concentration, muscle pH, drip loss, and fresh meat color to validate the head/heart electrical stunning method for small slaughter plants. Incidence of corneal reflex was not different between head/heart (93.8%) and head only (85%) stunning. Nose twitching was more common in head only (26.5%) than head/heart (5%) stunning. Head/ heart stunning eliminated rhythmic breathing, natural blinking, eye tracking to moving objects, and righting reflex, which were all observed in head-only stunned pigs. Eye tracking to moving objects was observed in 40.8% of head-only stunned pigs. Blood lactate was not different between stunning methods (head only: 8.8mmol/L, head/heart: 7.8mmol/L). Stun-to-bleed time did not differ (head only: 32s, head/heart: 33s). Mean time to loss of heartbeat with the head-only method was 121s. No heartbeat was observed with the head/heart method. Longissimus thoracis pH, color, and drip loss were not different between stunning methods. This study determined that the head/heart electrical stunning method reduces the incidence of signs of return to sensibility without significant effects on meat quality, plant operation speed, or blood lactate concentration. In addition, the head/heart method requires no capital investment for plants that are currently using the head-only method.

For more information the full article can be found at http://jas.fass.org/

Yeast culture supplement during nursing and transport affects immunity and intestinal microbial ecology of weanling pigs

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The objectives of this study were to determine the influence of a Saccharomyces cerevisiae fermentation product on innate immunity and intestinal microbial ecology after weaning and transport stress. In a randomized complete block design, before weaning and in a split-plot analysis of a 2 × 2 factorial arrangement of yeast culture (YY) and transport (TT) after weaning, 3-d-old pigs (n = 108) were randomly assigned within litter (block) to either a control (NY, milk only) or yeast culture diet (YY; delivered in milk to provide 0.1 g of yeast culture product/kg of BW) from d 4 to 21. At weaning (d 21), randomly, one-half of the NY and YY pigs were assigned to a 6-h transport (NY-TT and YY-TT) before being moved to nursery housing, and the other one-half were moved directly to nursery housing (NY-NT and YY-NT, where NT is no transport). The yeast treatment was a 0.2% S. cerevisiae fermentation product and the control treatment was a 0.2% grain blank in feed for 2 wk. On d 1 before transport and on d 1, 4, 7, and 14 after transport, blood was collected for leukocyte assays, and mesenteric lymph node, jejunal, and ileal tissue, and jejunal, ileal, and cecal contents were collected for Toll-like receptor expression (TLR); enumeration of Escherichia coli, total coliforms, and lactobacilli; detection of Salmonella; and microbial analysis. After weaning, a yeast × transport interaction for ADG was seen. Transport affected ADFI after weaning. Yeast treatment decreased hematocrit. A yeast × transport interaction was found for counts of white blood cells and neutrophils and for the neutrophil-tolymphocyte ratio. Monocyte counts revealed a transport effect. Interactions of yeast × transport and yeast × transport × day for TLR2 and yeast × transport for TLR4 expression in the mesenteric lymph node were detected. Day affected lactobacilli, total coliform, and E. coli counts. More pigs were positive for Salmonella on d 7 and 14 than on d 4, and more YY-TT pigs were positive on d 4. The number of bands for microbial amplicons in the ileum was greater for pigs in the control treatment than in the yeast treatment on d 0, and this number tended to decrease between d 1 and 14 for all pigs. Similarity coefficients for jejunal contents were greater for pigs fed NY than for those fed YY, but pigs fed YY had greater similarity coefficients for ileal and cecal contents. The number of yeast × transport × day interactions demonstrates the complexity of the stress and dietary relationship.

For more information the full article can be found at http://jas.fass.org/

Changes of the activities of glycolytic and oxidative enzymes before and after slaughter in the longissimus muscle of Pietrain and Duroc pigs and a Duroc-Pietrain crossbreed

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After slaughter of pigs, the pH of the meat decreases due to lactate accumulation within the tissue. In addition to calcium homeostasis, energy metabolism plays a key role during the muscle-to-meat transition, and it is interesting to know how specific enzymes of the glycolytic and oxidative pathways change during this process, especially in relation to the antemortem situation, and if there is an impact of these alterations on the meat quality characteristics. Therefore, in the present study samples of the LM from the pig genetic groups Pietrain (Pi), Duroc (Du), and a Du × Pi crossbreed population (DuPi) were collected 24 h before as well as 1 min, 40 min, and 12 h after slaughter, and the activities of the glycogen phosphorylase (GP), phosphofructokinase (PFK), lactate dehydrogenase (LDH), citrate synthase (CS), NADH-ubiquinone oxidoreductase (complex I), and cytochrome oxidase were analyzed. Additional investigations include carcass and meat quality characteristics as well as the microstructure of the LM. The Pi breed had greater carcass yield and lean meat values, but no differences of the meat quality traits could be determined between the investigated pig breeds. The Pi pigs exhibited a greater percentage of fast-twitch glycolytic and had smaller amounts of slow-twitch-oxidative fibers in comparison with the Du pigs. The enzyme activities of the GP, PFK, and complex I increased immediately after slaughter (1 min postmortem) of the pigs and the activity of the LDH within 40 min postmortem. After 12 h, the GP, PFK, LDH, and complex I activities decreased to the amount of the preslaughter sample. No differences could be found with regard to the enzyme activities of the CS and cytochrome oxidase at all determination times. Considering the enzyme activities within the different breeds, the Pi pigs exhibited greater GP and PFK and the Du animals exhibited greater CS and complex I activities. The study indicates that the glycolytic enzymes GP, PFK, and LDH as well as the complex I influence the muscle-to-meat transition process after slaughter of the animals without an impact on the muscle quality. The activities of the GP, PFK, CS, and complex I reflect the differences of the muscle fiber composition between the Pi and Du pigs.

For more information the full article can be found at http://jas.fass.org/

Immune response and blood chemistry of pigs fed conjugated linoleic acid

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Immune function (response to concanavalin A, cytokine production, and lymphocyte profiles) and blood chemistry variables were measured in growing-finishing pigs (Yorkshire/Landrace/Duroc dam × Hampshire sire) fed varying percentages of CLA (0, 0.12, 0.25, 0.50, and 1.0%). Blood was collected at 0, 14, 28, 42, and 56 d on feed (DOF). Total white blood cell (WBC) count increased linearly to 42 DOF. No differences were observed for WBC across CLA treatment. Nitric oxide was greater for the 1.0% CLA treatment compared with all other treatments. Flow cytometry using fluorescent labeled monoclonal antibodies to the CD4, CD8, double-positive CD4/CD8, and CD2 surface markers was used to determine lymphocyte subpopulations. Supplementation of CLA had no effect on lymphocyte subpopulation cell distribution. Most blood chemistry variables were within the normal metabolic range for pigs. A decrease was observed over DOF for P and K. Additionally, Na and Cl concentrations increased from 14 to 28 DOF and decreased over the remainder of the trial. Electrolyte balance was not different across CLA treatments and was likely explained by no differences in feed intake among the CLA treatment groups. Blood lipid variables indicated that total cholesterol, triglycerides, high density lipoproteins, and low-density lipoproteins increased as the amount of CLA in the diet increased, but none of the results from these treatments exceeded the normal range of acceptability. These results suggested that CLA was safe when fed to growing-finishing pigs and had little effect on their immune function and blood chemistry variables.

For more information the full article can be found at http://jas.fass.org/

Lactulose as a marker of intestinal barrier function in pigs after weaning

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Intestinal barrier function in pigs after weaning is almost exclusively determined in terminal experiments with Ussing chambers. Alternatively, the recovery in urine of orally administered lactulose can be used to assess intestinal permeability in living animals. This experiment was designed to study the barrier function of the small intestine of pigs over time after weaning. The aim was to relate paracellular barrier function (measured by lactulose recovery in the urine) with macromolecular transport [measured by horseradish peroxidase (HRP) using Ussing chambers] and bacterial translocation to assess whether lactulose recovery is related to possible causes of infection and disease. Forty gonadectomized male pigs (6.7 kg) were weaned (d 0) at a mean age of 19 d, fitted with urine collection bags, and individually housed. Pigs were dosed by oral gavage with a marker solution containing lactulose (disaccharide) and the monosaccharides l-rhamnose, 3-Omethylglucose, and d-xylose at 2 h and at 4, 8, and 12 d after weaning. The recovery of sugars in the urine was determined over 18 h after each oral gavage. The day after each permeability test, the intestines of 10 pigs were dissected to determine bacterial translocation to the mesenteric lymph nodes and jejunal permeability for HRP in Ussing chambers. Recovery of l-rhamnose in urine was affected by feed intake and by the time after weaning. Recovery of lactulose from the urine was greater at 4, 8, and 12 d after weaning compared with the first day after weaning and was negatively correlated with feed intake. The mean translocation of aerobic bacteria to the mesenteric lymph nodes was greater at 5 and 13 d after weaning compared with d 1. Lactulose recovery showed no correlation with permeability for HRP nor with bacterial translocation. Although both lactulose recovery and bacterial translocation increased over time after weaning, lactulose recovery did not correlate with the permeability for HRP nor bacterial translocation within a pig. Therefore, we conclude that lactulose recovery in the urine of pigs after weaning is not associated with risk factors for infections. However, it appears to be possible to measure paracellular barrier function with orally administered lactulose in pigs shortly after weaning. Further studies will reveal whether this variable is relevant for the long-term performance or health of pigs after weaning.

For more information the full article can be found at http://jas.fass.org/

Effect of source and quantity of dietary vitamin D in maternal and creep diets on bone metabolism and growth in piglets

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Piglets are born with reduced plasma concentrations of 25-hydroxycholecalciferol (25-OH-D3) and are thus highly predisposed to vitamin D deficiency. Furthermore, sow milk contains little vitamin D, and the slow intestinal vitamin D absorption of sows limits the efficacy of dietary vitamin D supplementation. Hence, the neonate depends, to a large extent, on the vitamin D stores built up in fetal tissues from maternal sources. The current study was undertaken to evaluate whether the source and quantity of dietary vitamin D provided to the gestating and lactating sow, and also directly in the form of creep feed to the piglet, would influence the vitamin D status, growth performance, and skeletal development of piglets. A total of 39 primiparous and multiparous sows were randomly assigned to 1 of 3 dietary treatments (13 in each treatment), supplemented with either 5 or 50 μg of the commonly used cholecalciferol (vitamin D3) or 50 μg of 25-OH-D3 per kilogram of feed. By wk 3 of lactation, piglets were offered a creep diet with vitamin D supplementation according to the treatment of the dam, and they were offered the same creep diets after weaning at d 35 of age until they reached a BW of approximately 20 kg. When dietary 25-OH-D3 was provided, circulating concentrations of 25-OH-D3 in piglet serum increased as early as d 21 and later at d 33 and 77, indicating greater body stores in those animals. Bone-breaking strength and cortical bone mineral content and density at the tibial midshaft of piglets were reduced when vitamin D3 was supplemented at 5 μg/kg compared with the bone traits of other groups, but no differences were observed between the 2 other groups. After weaning, ADFI was greater and growth performance tended to improve when doses of 50 μg/kg were administered, regardless of the vitamin D source. In conclusion, supplementation of the diet with 50 μg/kg of either source of vitamin D was proved to be adequate in meeting the needs of gestating sows and in permitting the accumulation of vitamin D in J ANIM SCI 2011, 89:1347-1357fetal tissues, as well as for normal skeletal mineralization and growth in the offspring. Furthermore, the markedly improved vitamin D status of piglets whose mothers received 25-OH-D3 possibly resulted from greater tissue reserves present at birth and a greater availability of vitamin D when released from those stores.

Statistical tools to detect genetic variation for a sex dimorphism in piglet birth weight

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Sex differences in birth weight contribute to within-litter variability, which itself is connected to piglet survival. Therefore, we studied whether the sex difference in piglet birth weight is a genetically variable sex dimorphism. For that purpose a linear mixed model including sex-specific additive genetic effects was set up. A hypothesis testing problem was defined to detect whether these genetic effects significantly differ between sexes. In a second step, the effect of sex-linked genes was studied explicitly by partitioning the additive genetic effects into autosomal and gonosomal effects. Furthermore, a definition of heritability for the sex difference of a randomly chosen pair of littermates with opposite sex was given. The proposed models were applied separately to a Landrace and Large White data set. Significant genetic variability for the sex dimorphism was found in Landrace but not in Large White. Heritability estimates were at 3 to 5% depending on the model. The X-chromosomal genetic variation was not significant at all, whereas the Y-chromosome significantly contributed to the genetic variation in Landrace with a corresponding SD of 34 g. It can be concluded that the sex dimorphism of piglet birth weight is genetically variable and a potential target of genetic improvement.

For more information the full article can be found at http://jas.fass.org/

Claw lesions in lactating sows on commercial farms were associated with postural behavior but not with suboptimal reproductive performance or culling risk

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Claw lesions in lactating sows on 3 commercial farms were assessed in 6 areas of each of a sow’s 8 claws to investigate the relationship between claw lesions and stage of lactation. In addition, the relationships between claw lesions and postural behavior, reproductive performance or culling risk were investigated. We used a 5-point score method (0, 1, 2, 3 or 4) for each claw area and overgrown heel was additionally scored. Total sow-lesion score (TSLS) for each sow was obtained by summing the scores for the 6 areas of the 8 claws. The highest claw lesion score for each sow was defined as the highest claw lesion score (HCLS) recorded in the 48 claw areas. We recorded the relative frequency (%) of postural behavior by point sampling at 15-min intervals over a 6 h period. Linear mixed-effects models were used for statistical analyses. Of the 308 sows observed, mean TSLS was 17.3±0.40. Proportions of sows with HCLS 0, 1, 2, 3 and 4 were 0.0, 43.5, 50.6, 4.9 and 1.0%, respectively. The heel area had the highest proportions of claw-lesion score 2 or higher between the 6 areas. There were more claw-lesion scores of 2, 3, and 4 in the hind limbs of lateral claws than in the front limbs. High TSLS or HCLS was not related to the stage of lactation and no differences were found between HCLS groups or TSLS groups for overall culling risk after weaning. There were no differences between TSLS groups for adjusted 21-day litter weight, preweaning mortality or weaning-to-first-mating interval. No differences were found between HCLS groups for the sow performance, although sows in the high TSLS group had a higher farrowing percentage than those in the low TSLS group. There were no differences between HCLS groups for postural behavior, but sows in the high-TSLS group had the highest relative frequency of lying posture and the lowest frequency of standing posture. In summary, claw lesions in lactating sows were not related to negative reproductive performance and culling risk, but there was a relationship with postural behavior.

For more information the full article can be found at http://www.journals.elsevierhealth.com/periodicals/livsci

Growth performance and antibiotic tolerance patterns of nursery and finishing pigs fed growth-promoting levels of antibiotics

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The objective of this study was to evaluate the impact of growth-promoting levels of antibiotics in diets for nursery and finishing pigs on growth performance and antibiotic tolerance patterns. Gilts (n=200, initial body weight was 6.2±0.003 kg), were allotted based on body weight to one of four treatments in a 2×2 factorial randomized complete block design. Nursery treatments consisted of feeding no antibiotics (CON) or an antibiotic diet (ANTI) containing chlortetracycline (CTC; 55mg/kg). At the end of the nursery phase, one-half of the pigs receiving CON were switched to a diet containing antibiotic (virginiamycin; VIR, 11 mg/kg) and one-half of the pigs receiving ANTI were switched to CON for the remainder of the trial. This created four treatments for the finishing phase, consisting of: control in nursery and finishing (CC), antibiotic in nursery, control in finishing (AC), control in nursery, antibiotic in finishing (CA), or antibiotics throughout (AT). The pigs were weighed at the diet changes during the nursery (weeks 1, 3, and 5) and finishing (weeks 7, 9, 13, 17, and 20) phases. Fecal samples were collected at all diet changes for isolation of fecal coliforms and Enterococcus and subsequently tested for tolerance to CTC and VIR. After 1 week, CON pigs weighed less (7.09 vs. 7.28 kg) and had lower ADG(149 vs. 180 g/day) and ADFI (174 vs. 192 g/day) than ANTI pigs. No performance differences were observed during the remainder of the study. At the initiation of the study (week 0), the ability of coliforms to grow in the presence of CTC and VIR, respectively, were 68 and 73% and increased to 90 and 96% at week 19 (time effect). At week 17, tolerance of coliforms to CTC was greater for CA (98%) than AC (86%, time×treatment effect, Pb0.004). Enterococcus tolerance to CTC at week 7 was lower for CC (55%) compared to AT (76%), AC (74%) and CA (83%, time×treatment effect). At week 9, Enterococcus tolerant to CTC and VIR, respectively, was lower for CC (15 and 18%) than AT (31 and 40%), AC (35 and 35%), and CA (44 and 43%, time×treatment effect). Antibiotic growth promoters had little impact on growth performance in clean, isolated facilities with high labor inputs. The tolerance of bacteria to antibiotics fluctuated over time and persisted regardless of the use of antibiotic growth promoters.