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The aim was to investigate the effect of weaning age, weaning weight, and nursery feeding regime on post-weaning performance. The focus was on pigs weaned light, as they may be better off when weaned at a later age and/or offered a specialist nursery feeding regime. Piglets (n = 1,448) from one farrowing batch of 110 sows that farrowed over 2 wk were individually weighed and their morphometric measurements were taken at birth. Pigs were weaned on the same day, but variation in birth date resulted in variable weaning ages (mean age day 34.1, SD = 2.5). The youngest 50% at weaning were classified Y and the oldest 50% as O; within an age class, the lightest 50% were classified L, the heaviest 50% as H, and housed accordingly. Pigs were individually weighed at weaning, 7 and 15 wk post-weaning. At weaning, Y were 6 d younger and 1.4 kg lighter than O pigs, whereas L were 3.2 kg lighter than H pigs. Pigs were randomly allocated to a 3-stage superior (SUP) or control (CON) nursery feeding regime, with SUP pigs having a 65% greater allowance (on a kg/pig basis) of the first and second stage feeds than the CON. Pigs weaned Y had a higher mortality rate from weaning to 7 wk post-weaning than pigs weaned O (9.14% vs. 4.98%; P = 0.046). As expected, age and weight significantly (P < 0.001) affected performance to both 7 and 15 wk post-weaning: at 15-wk pigs weaned Y were 5.5 kg lighter than pigs weaned O; pigs weaned L were 9.0 kg lighter than H pigs. It was estimated that pigs weaned YL needed ~4 d more (P = 0.018) to reach 60 kg BW than pigs weaned OL. Feed intake was not affected by feeding regime, age and weight, or their interactions. Performance was not affected by feeding regime (P > 0.05), but was affected by the weight × feeding regime interaction (P = 0.044) to 7 wk post-weaning: L pigs on SUP were 1.2 kg heavier than L pigs on the CON regime; this was not the case for the H pigs. Performance up to 7 wk post-weaning was positively associated with birth weight to cranial circumference ratio and weaning weight (P < 0.05) for both YL and OL pigs; for the latter, additional performance predictors were weaning age (P = 0.044) and feeding (P = 0.027). Improved growth for L pigs up to 7 wk post-weaning could be obtained by a greater allowance of the nursery diets. However, weaning at a later age benefitted the performance of L pigs to a common BW, suggesting that this might be a strategy with longer term benefits., (© The Author(s) 2019. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The Teagasc Pig Production Model (TPPM), a stochastic simulation model of a farrow-to-finish pig farm, was developed to investigate effects of changes in production systems on farm profitability. The model simulates, on a weekly basis, the annual production of a farm. Biological [e.g., herd size, number of litters/sow/year, and mortality rates (%)], physical (e.g., infrastructure), and technical (e.g., feeding practices) variables and their associated costs are included as components of the model. These inputs are used to calculate physical (e.g., feed usage and number of pigs slaughtered) and financial (e.g., annual cash flow, profit and loss account, and balance sheet) outputs. The model was validated using the Delphi method and by comparing the TPPM outputs to data recorded on 20 Irish pig farms through the Teagasc e-Profit monitor system and with complete receipts for the year 2016. Results showed that the TPPM closely simulates physical and financial performance of pig farms indicating that the TPPM can be used with confidence to study pig production systems under Irish conditions. Model applicability was demonstrated by investigating the impact of 2 changes in technical performance: 1) building of extra accommodation to increase body weight (BW) at sale by 15 kg (EXTRA ROOM) and 2) a change in feeding practices by providing finisher feed from 28 kg of BW (EARLY FINISHER) compared with over 38 kg of BW. In both scenarios, the same biological parameters were used. Mortality rates, feed ingredients costs, and price per kg of meat produced were included as stochastic variables with the input distributions derived based on historical data simulated using Monte Carlo sampling using the Microsoft Excel add-in @Risk. Annual mean net profit was €198,101 (90% confidence interval [CI]: €119,606-€275,539) for the TPPM base farm, €337,078 (90% CI: €246,320-€426,809) for the EXTRA ROOM, and €225,598 (90% CI: €146,685-€303,590) for the EARLY FINISHER. EXTRA ROOM was associated with higher costs and required higher income to cover the additional costs. The 90% CI of the EARLY FINISHER was similar to the TPPM base farm while the EXTRA ROOM scenario resulted in a wider confidence interval, suggesting that a change in feeding practices could be a better option for farmers looking to improve profit with minimum investment. Thus, the TPPM could be used to facilitate decision making in farrow-to-finish pig farms., (© The Author(s) 2019. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Disease is a leading cause of diminished welfare and productivity in pig systems, but its spread among pigs within commercial herds can be limited through early detection. Identifying specific behavioral changes at the onset of disease can have a substantial diagnostic value by improving treatment success through timely intervention. Our study aimed to identify key behaviors that visibly change at the group level when only a few individuals are acutely sick. First, we quantified the behavioral changes seen during an acute health challenge in groups of pigs, using total pen vaccination as an artificial sickness model. Then we investigated the minimum proportion of sick pigs needed to detect group level behavioral changes using three treatments: a control (Con; 0% pigs), low (±20% pigs), or a high (±50% pigs) number of pigs vaccinated in the pens. Total pen vaccination in Trial 1 produced group level behavioral changes, including reduced feeding (P < 0.001), non-nutritive visits to the feeder (P < 0.01), drinking (P < 0.001), standing (P < 0.001), and interaction with pen enrichment (P < 0.001), accompanied by increased lying rates (P < 0.01) and elevated body temperatures (P < 0.001), confirming that vaccination is an appropriate model to study effects of acute sickness. In Trial 2, group level declines in interaction with the enrichment device (P < 0.001) and standing rates (P = 0.064), along with an increase in pen lying rates (P < 0.001), were apparent in the Low treatment when compared to the Con rates, which suggests these key behaviors could serve an important diagnostic value for early disease detection in groups. These changes lasted for up to 3 h post vaccination. In contrast, feeding rates (treatment × time of day: P < 0.01) only showed a decrease from the Con in the High treatment after vaccination, with pen drinking showing a similar trend (treatment: P = 0.07), suggesting that these behaviors would be more appropriate for confirming the spread of disease within a herd. Identifying key behaviors that alert to the presence of disease is critical to further refine automated early warning systems using pen level sensors for commercial pig operations., (© The Author(s) 2019. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

To improve the performance of lightweight piglets during suckling, producers are advised to create uniform litters using young sows. However, fostering piglets to primiparous sows may confer penalties due to their lower milk yield and milk immunoglobulin concentrations compared with multiparous sows. The objective was to determine the effect of foster sow parity (primiparous (F), second (S), and mid parity (M: parity 3 to 5)) on the performance from birth to day 68 of piglets born light (L: ≤1.25 kg) or heavy (H: 1.50-2.00 kg) and on creep feed consumption. Piglets (n = 507) considered L or H were cross-fostered, creating litters of 13 similar-sized piglets/litter and were randomly fostered to one of the foster parities. All litters were offered creep feed with a green dye to discern between consumers and nonconsumers, and the medication administered was recorded. Medication administrated pre- and postweaning did not differ (P > 0.05) across the different experimental groups. A significantly (P ≤ 0.025) lower number of H piglets were removed as a result of preweaning weight loss from F and S, rather than M litters. The interaction between birth weight and foster parity only affected piglet BW at day 10 (P = 0.020); foster parity did not influence BW of L piglets, but influenced that of H piglets. H piglets in F and M litters (3.82 and 3.80 kg) were significantly lighter (P ≤ 0.013) than H piglets in S litters (4.15 kg). As expected, L piglets performed worse pre- and postweaning than H piglets; they were 4.50 kg lighter at day 68. Foster parity significantly affected BW: F piglets were weaned lighter (P = 0.004) than S and M piglets (7.52 vs. 8.02 kg). Postweaning (day 68) however, F piglets achieved similar BW as S piglets (29.7 vs. 29.9 kg), whereas M piglets performed best (31.2 kg, P ≤ 0.079). Significantly fewer (almost none) of the L than the H piglets consumed creep feed (P < 0.001); significantly (P = 0.007) more F and M piglets were considered consumers than S piglets. The results suggest that irrespectively of birth weight, piglets tend to perform better when in M litters, being weaned heavy and having a high creep feed intake; however, more piglets are removed from such litters preweaning. Although S litters were weaned heavy, they were unable to maintain this BW advantage postweaning, due to their low creep feed intake and F litters remained small throughout. Long-term performance monitoring to slaughter is recommended., (© The Author(s) 2019. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Major improvements in sow prolificacy have resulted in larger litters but, at the same time, increased the proportion of piglets born light weight. Different management strategies aim to enhance the performance of, and limit light-weight piglet contribution to, BW variation within a batch; however, consequences on heavy-weight littermates are often neglected. This study investigated the effects of different litter compositions, created through cross-fostering, and the provision of creep feed on preweaning behavior and short- and long-term performance of piglets born either light weight (≤1.25 kg) or heavy weight (1.50-2.00 kg). Piglets were cross-fostered at birth to create litters with only similar-sized piglets (light weight or heavy weight; UNIFORM litters) and litters with equal numbers of light-weight and heavy-weight piglets (MIXED litters); half of the litters were offered creep feed and the remaining were not. Piglet behavior during a suckling bout and at the creep feeder was assessed; a green dye was used to discern between consumers and nonconsumers of creep feed. The interaction between litter composition and birth weight (BiW) class influenced piglet BW at weaning ( < 0.001): piglets born light weight were lighter at weaning in MIXED litters than those in UNIFORM litters (6.93 vs. 7.37 kg); however, piglets born heavy weight performed considerably better in MIXED litters (8.93 vs. 7.96 kg). Total litter gain to weaning was not affected ( = 0.565) by litter composition. Teat position affected heavy-weight piglet performance by d 10 ( < 0.001), with heavy-weight piglets in UNIFORM litters being disadvantaged when suckling the middle and posterior teats. Creep feed provision did not affect BW at weaning ( > 0.05) for either BiW class. However, litter composition significantly affected daily creep feed consumption ( = 0.046) and fecal color ( = 0.022), with heavy-weight piglets in UNIFORM litters consuming the highest amount of creep feed and having the greenest feces. In addition, a lower number of heavy-weight piglets in UNIFORM litters were classified as nonconsumers ( = 0.002). The weight advantage heavy-weight and light-weight piglets had at weaning when reared in MIXED and UNIFORM litters, respectively, was sustained throughout the productive period. In conclusion, reducing BW variation within litter (UNIFORM litters) was beneficial for piglets born light weight but not for piglets born heavy weight; the latter were disadvantaged up to slaughter. Although heavy-weight piglets in UNIFORM litters consumed the greatest amount of creep feed, this was not able to overcome their growth disadvantage compared with heavy-weight piglets in MIXED litters.

The regulation of the drinking behavior of animals is usually overlooked, and the traits associated with it are not well defined. We used a unique data set of measurements of individual drinking behavior in turkeys 1) to validate the system of data generation, 2) to develop a methodology to allow clustering of drinking events and splitting behavior into bouts, and 3) to develop traits related to drinking behavior and its regulation and investigate how these traits may be affected by bird genotype. Visits to drinkers were generated by an electronic, custom-made equipment that automatically measures the individual drinking behavior of a large number of turkeys from 3 different genetic lines. The overall reliability of the electronic system was estimated from video observations and resulted in a predictability of 98.8% and sensitivity of 98.6%. A novel method based on mixture distribution models allowed clustering of drinking events and splitting behavior into bouts by estimating the shortest interval between visits to the drinker that was considered to be part of a bout (bout criterion). The method predicted that after the end of a given bout the probability of the bird initiating the next bout was low but increased with time since the last bout. As a result, drinking bouts were not randomly distributed but were predicated on the physiological principle of satiety, suggesting that they constitute biologically appropriate units for expressing drinking behavior. The applied method resulted in bout criteria estimates of 665, 672, and 602 s for genetic lines A, B, and C, respectively. On the basis of this methodology, a number of drinking behavior traits, such as bout duration and frequency, and water intake per bout were identified that revealed differences ( < 0.01) in the drinking behavior between the turkey genetic lines. Similarly, time accumulation patterns of drinking behavior traits within a day differed ( < 0.01) within and between genetic lines, suggesting that variation in drinking behavior exists and birds use different behavioral strategies to meet their water intake requirements. Development of drinking behavior over time was similar between the lines, suggesting conservation of this behavioral organization. As well as providing ideas about the regulation of drinking behavior, the developed behavioral traits may be of practical relevance because water utilization, along with feed efficiency, is part of overall biological efficiency.

Birth weight (BiW) of pigs is a commonly used predictor of postnatal performance; however, it has been suggested that morphological measurements may be more reflective of the intrauterine environment and thus better predictors of postnatal growth. The aim of this study was to determine 1) whether morphological measurements, including ponderal index (PI), body mass index (BMI), and abdominal circumference (AC), could be used as predictors of postnatal performance and 2) if so, would they be better predictors than BiW and 3) would the same predictors apply to pigs of different BiW at different stages of their growth? Morphological measurements, BiW, and BW at d 28 and 70 were available for 731 pigs from experiments conducted over a 2-yr period. A series of linear models was used to determine predictors that affected growth performance from birth to d 28 and from d 28 to 70. For both light (LBiW; ≤1.25 kg) and normal BiW pigs (NBiW; 1.60 to 2.00 kg), BiW was not the best predictor of performance ( > 0.05); different variables for the growth periods considered applied to pigs with different BiW. For LBiW pigs BMI ( < 0.001) and AC ( = 0.0202) were the best predictors for d 1 to 28, and AC ( = 0.0317) and PI ( = 0.0450) were the best predictors from d 28 to 70, with pigs with a larger AC and higher PI/BMI more likely to have higher ADG pre- or postweaning. In contrast, the best predictor variables for NBiW pigs were AC ( = 0.0482) for d 1 to 28 and crown-rump length (CRL; = 0.0138) for d 28 to 70. Focusing on LBiW pigs with low ADG, BMI was the best predictor ( < 0.05) of growth for pre and postweaning, whereas for LBiW pigs with high ADG the best predictors were AC ( = 0.00132) from d 1 to 28 and BiW ( = 0.00601) from d 28 to 70, with increasing BMI, AC, and BiW associated with greater ADG. For NBiW pigs with high preweaning ADG, the best predictor consisted solely of AC ( 0.0210), but no morphological predictor variables were significant for NBiW pigs with low preweaning ADG. For d 28 to 70, the best predictor for NBiW pigs with low ADG was CRL ( = 0.0171), but for high ADG no predictor variables were significant. The present study showed that the morphology of piglets is more important than BiW when predicting the postnatal growth of pigs; however, which measurement is the most important depends on both the BiW and stage of growth. For small-sized pigs, these morphological measures may be considered as a decision-making tool by farmers when trying to identify potential poor performers.

The objective of the study was to develop a life cycle assessment (LCA) for pig farming systems that would account for uncertainty and variability in input data and allow systematic environmental impact comparisons between production systems. The environmental impacts of commercial pig production for 2 regions in Canada (Eastern and Western) were compared using a cradle-to-farm gate LCA. These systems had important contrasting characteristics such as typical feed ingredients used, herd performance, and expected emission factors from manure management. The study used detailed production data supplied by the industry and incorporated uncertainty/variation in all major aspects of the system including life cycle inventory data for feed ingredients, animal performance, energy inputs, and emission factors. The impacts were defined using 5 metrics-global warming potential, acidification potential, eutrophication potential (EP), abiotic resource use, and nonrenewable energy use-and were expressed per kilogram carcass weight at farm gate. Eutrophication potential was further separated into marine EP (MEP) and freshwater EP (FEP). Uncertainties in the model inputs were separated into 2 types: uncertainty in the data used to describe the system (α uncertainties) and uncertainty in impact calculations or background data that affects all systems equally (β uncertainties). The impacts of pig production in the 2 regions were systematically compared based on the differences in the systems (α uncertainties). The method of ascribing uncertainty influenced the outcomes. In eastern systems, EP, MEP, and FEP were lower (P < 0.05) when assuming that all uncertainty in the emission factors for leaching from manure application was β. This was mainly due to increased EP resulting from field emissions for typical ingredients in western diets. When uncertainty in these emission factors was assumed to be α, only FEP was lower in eastern systems (P < 0.05). The environmental impacts for the other impact categories were not significantly different between the 2 systems, despite their aforementioned differences. In conclusion, a probabilistic approach was used to develop an LCA that systematically dealt with uncertainty in the data when comparing multiple environmental impacts measures in pig farming systems for the first time. The method was used to identify differences between Canadian pig production systems but can also be applied for comparisons between other agricultural systems that include inherent variation.

A meta-analysis on the effects of management and animal-based factors on the reproductive efficiency of gestating sows can provide information on single-factor and interaction effects that may not have been detected in individual studies. This study analyzed the effects of such factors on the number of piglets born alive per litter (BA), piglet birth weight (BiW) and weaning weight (WW), and number of piglets born alive per kilogram of sow feed intake during gestation (BA/FI). A total of 51 papers and 7 data sources were identified for the meta-analysis, out of which 23 papers and 5 sets of production data were useable (a total of 121 treatments). The information gathered included the dependent variables as well as information regarding animal, management, and feed characteristics. While a number of factors were individually significant, the multivariate models identified significant effects only of 1) floor type (P=0.003), sow BW at the end of gestation (P=0.002), and housing (stalls vs. loose; P=0.004) on BA; as floor type and housing were confounded, they were included in 2 separate models. The BA was higher on solid (12.1) in comparison to partly slatted (11.4) and fully slatted floors (10.2); 2) sow gestation environment (P=0.017) and gestation feed allowance (P=0.046) on BiW, with BiW of pigs higher for sows kept outdoors rather than indoors (1.75 versus 1.49 kg); 3) parity number (P=0.003) and feed intake during gestation (P=0.017) on WW; in addition there was an interaction between parity number×feed ME and parity number×feed CP content of feed during gestation on WW, with the positive effects of feed ME and CP contents seen during early rather than later parities; and 4) floor type (P=0.019) and feed crude fiber (P=0.003) for BA/FI with a greater number for those kept on solid floors (5.11) versus partially and fully slatted floors (4.07 and 4.05). The meta-analysis confirmed the significant effect of several well-known factors on the efficiency of gestating sows and, importantly, the interactions between these factors. In addition, the effects of some less established factors were noted, such as floor type. The results may contribute towards the improvement of efficiency of gestating sow systems by better understanding of the various factors that influence this.

Low birth weight pigs are on a different growth trajectory from their normal birth weight littermates and as a consequence they may need to be fed differently, if they are to show compensatory gain. The objective of the experiment was to determine if low birth weight pigs will respond to a higher AA: energy diet, in a manner similar to the response of normal birth weight pigs whose BW gain has been previously reduced as a result of feed restriction. The experiment was a 3 × 2 factorial with 180 pigs and 6 replicates. Treatments were comprised of 3 BW categories (NU = normal birth weight fed unrestrictedly [1.7 to 2.0 kg], NR = normal birth weight but fed restrictedly from d 49 to 63 and L = low birth weight [ ≤ 1.2 kg]) and 2 diet specifications given from d 63 to 91 (high or standard AA: energy ratio). In period 1 (d 0 to d 49), pigs were selected within 24 h of birth and cross fostered into litters by birth weight (11/12 piglets). Pigs were weaned at d 28 and kept in their litters until d 49. In period 2 (d 49 to 63), litters were split to form 2 treatment groups consisting of 5 pigs each: NR pigs received restricted amounts of feed (600 g/d) with the remaining NU and L pigs fed ad libitum on a conventional diet. The aim was for NR and L pigs to have the same BW by d 63. In period 3 (d 63 to 91), groups within litter were randomly allocated to a high or standard AA:energy ratio diet. Body weight on d 63 was 25.8, 21.2, 21.8 kg (0.381 SED) for NU, NR and L pigs respectively; by d 91 there was no difference in the BW of NU and NR pigs (P > 0.05), but L pigs still weighed less (P < 0.001). There was a significant effect of BW category and diet specification during period 3 on the ADG and G:F of pigs (P < 0.05), with NR pigs exhibiting higher ADG and G:F than L and NU pigs. For G:F only, there was a tendency towards significance for an interaction (P = 0.057) with NU and NR pigs having an improved G:F on the high specification diet, but L pigs did not. Average daily feed intake was similar for all BW categories and diets from d 63 to 91. However, both L and NR pigs consumed more feed than NU pigs relative to their BW, but only NR exhibited higher ADG than NU pigs. This suggests that a higher specification diet post weaning may not improve the performance of low birth weight pigs. However, previously restricted normal birth weight pigs were able to exhibit compensatory growth and were more efficient when fed a higher specification diet.

Piglets born with low birth weights (LBiW) are likely to be lighter at weaning. Starter regimes tailored for pigs of average BW therefore may not be optimal for LBiW nursery performance. The objective was to determine if LBiW pigs benefit from a high specification starter regime and the provision of extra feed (additional allowance of last phase diet of the starter regime) in comparison to a standard commercial regime. Additionally, the effect of starter regime on performance of normal birth weight (NBiW) pigs at weaning was determined and compared to that of LBiW pigs. Finally, the cost effectiveness of the treatments was determined. The experiment was therefore an incomplete 2 × 2 × 2 factorial design, as the provision of extra feed was given only to LBiW pigs (n = 6 replicates per treatment; 5 pigs per replicate). Treatments comprised birth weight (LBiW or NBiW), starter regime (high specification [HS] or standard starter [SS]), and extra feed 3 quantity (yes [YF] or no [NF], for LBiW pigs only; feed 3 corresponded to the last phase diet of the starter regime). At weaning (d 28), pigs were randomly assigned within each birth weight category to treatment groups. Nutritional treatments were fed ad libitum on a kilogram/head basis for approximately 3 wk followed by a common weaner diet fed ad libitum until d 70. Starter regime (P = 0.019), feed 3 amount (P = 0.010), and their interaction (P = 0.029) had an effect on ADG of LBiW pigs from d 28 to 49, with pigs on HS followed by YF (HY) performing best. An improvement in feed conversion ratio (FCR) was noted between d 28 and 49 for pigs fed the additional feed 3 (P = 0.030); between d 49 and 70, the only residual effect seen was of starter regime (P = 0.017) on ADG. In contrast, there was no significant effect of starter regime from d 28 to 70 on ADG, ADFI, or FCR of NBiW pigs. By d 49 and 70, LBiW pigs on regime HY weighed the same as NBiW pigs (d 70 BW; 30.0 vs. 30.6 kg; P = 0.413), with similar growth rates from d 28 to 70 (0.570 vs. 0.533 kg/d; P = 0.137). Despite highest feed cost for regime HY at US$12.30 per pig, its margin over feed was greatest ($23.40). Conversely, regime SS gave the best margin over feed for NBiW pigs at $22.70 per pig. In conclusion, a postweaning feeding regime formulated for LBiW pigs improved the ADG and FCR to the end of the nursery phase enabling them to achieve the same weight as NBiW. Targeting the provision of the high quality expensive regime only to light pigs will ensure maximum growth and increased profitability.

Performance of pigs from birth to slaughter is a result of a complex interaction of factors, with the early stages of a pig's life likely to affect lifetime performance. During the preweaning stage, piglets are reliant on the sow for nutrition, and sibling competition is likely to affect growth, in particular for low birth weight (LBiW) piglets. The objective of the experiment was to determine the effect of litter composition (littermate weight) and milk supplementation during lactation on the performance of LBiW pigs to weaning and the long-term consequences of treatment to slaughter. The experiment was a 2 × 2 factorial with littermate weight (normal or LBiW) and provision of supplementary milk from d 1 to 28 (yes or no) as factors. A total of 265 piglets were selected within 24 h of birth and cross-fostered to create 2 litter types (LOW = LBiW pigs [≤ 1.25 kg] only and MX = both LBiW and normal birth weight pigs [1.6 to 2.0 kg]); half of the litters within a type were supplemented with milk and the other half were not. The behavior of litters given milk was recorded to identify milk consumption patterns. Piglets were weaned at d 28 and kept in their litters until d 70 and then subsequently housed in mixed groups until slaughter. No difference was observed at any stage in the ADG of pigs given access to supplementary milk or not (P > 0.05) nor was there any significant interaction between milk provision and litter composition (P > 0.05). However, LOW litters drank significantly more supplementary milk than MX litters (P < 0.001). There was a significant effect of litter type on ADG from d 14 to 28, with LBiW pigs in LOW litters performing better than those in MX litters (0.252 versus 0.217 kg/d; P < 0.05). At weaning, LBiW piglets in LOW litters weighed over 500 g more than those in MX litters (P < 0.05). In MX litters there was a significant interaction between birth weight and supplementary milk on the CV of BW from d 14 to slaughter (P < 0.05). In conclusion, grouping LBiW piglets with similar sized littermates preweaning can improve preweaning performance by reducing competition from heavier littermates; however, this advantage does not persist after weaning. Although supplementary milk does not improve LBiW pig performance before or after weaning, it affects their drinking behavior and can reduce the variation in the BW of LBiW piglets in mixed litters to slaughter.

During the production period from birth to slaughter there are some pigs that grow markedly slower, despite conditions that seem to support the growth of their contemporaries. This reduction in growth inevitably leads to weight variation within a group, causes difficulties with management, and results in system inefficiencies. By understanding the factors that contribute to poor growth, the performance of these slow growing pigs might be improved, thereby decreasing the overall variability at slaughter. The aim of this paper was to analyze the factors associated with poor growth performance in pigs from birth to slaughter, determine the effect of piglet birth weight (BiW) and weaning weight (WW) on lifetime growth, and investigate the capacity of small piglets to compensate for any BW deficit. Two industry databases, with individual data for approximately 40,000 and 90,000 pigs, respectively, and containing BW profiles and relevant variables, were analyzed. Body weight at birth, weaning, intermediate, and finishing stages were available as well as sex, month of birth, litter size information (number born alive and total born including still born), sow parity number, and length of gestation. Absolute and relative growth rates, based on adjusted BW for age, were calculated for each time interval and 3 types of analysis were performed: a logistic regression, a continuous linear plateau model, and a weight category analysis. For both datasets poor absolute and relative growth from birth to final BW was associated with low BiW (P < 0.001), low WW (P < 0.001), sex (P < 0.001), breed code (P < 0.001), and month of birth (P < 0.001). The linear plateau model suggested that the relationship between BiW and lifetime growth was not linear beyond 1.91 (database 1) or 1.84 (database 2) kg; the same applied to the relationship between WW at 21 d and final BW (FW) growth, which was not linear beyond 7.53 kg. Finally, the weight category analysis revealed that piglets with the lightest BiW were able to exhibit compensatory growth from BiW to FW with 74 (database 1) and 82% (database 2) moving at least 1 BW category. It is concluded that growth performance to slaughter is not solely reliant on pig BiW, with WW also playing a critical role. Additionally, piglets with BiW below the average are capable of some degree of compensatory growth; this provides the opportunity for managing them so as to improve their lifetime growth.

To reduce reliance on imported soybean meal (SBM) in temperate environments, pea and faba bean may be alternative protein sources for pig diets. We assessed the effects of dietary pea and faba bean inclusion on grower and finisher pig performance and carcass quality. There were 9 dietary treatments tested on both grower (30 to 60 kg) and finisher (60 to 100 kg) pigs in a dose response feeding trial. The control diet included SBM at 14 and 12% for grower and finisher pigs, respectively, whereas in the test diets, pea or faba bean were included at 7.5, 15, 22.5, and 30%, gradually and completely replacing SBM. Diets were formulated to be isoenergetic for NE and with the same standard ileal digestible Lys content. After a 1-wk adaptation period, each diet was available on an ad libitum basis to 4 pens of pigs with 4 pigs per pen (2 entire males and 2 females) for 4 wk. Weekly BW for individual pigs, and pen intakes were recorded to assess ADG, ADFI, and G:F. Finisher pigs were then slaughtered at a commercial slaughter house to record carcass quality and assess skatole and indole concentration in the backfat. There were no effects (P > 0.10) on grower ADG, ADFI, and G:F, but pulse inclusion reduced finisher ADG (P = 0.04), with a quadratic effect of pulse inclusion (P = 0.03), as ADG tended to be reduced over initial inclusion levels only. There were no associated effects (P > 0.10) on ADFI or G:F, and pea and faba bean diets resulted in similar finisher performance. Increasing pulse inclusion linearly increased fecal DM content both in grower pigs (P = 0.02) and finisher pigs (P < 0.01). There were no effects on carcass quality or backfat skatole concentrations, but indole concentration was linearly reduced with increasing pulse inclusion (P = 0.05). It is concluded that pea and faba bean may be a viable alternative to SBM in grower and finisher pig diets.

Low P digestibility combined with intensive pig production can lead to water pollution. The aim of this paper was to develop a model able to represent P digestion in pigs across diets and contribute towards the reduction of P excretion. Phosphorus in plant feedstuffs includes some nonphytate P (NPP) that is readily digested but is mostly as organic phytate P (oP) that is indigestible unless it is dephosphorylated. The ability of pigs to dephosphorylate oP using endogenous phytase enzymes is limited and is a function of Ca intake. The effect of Ca (g/kg diet) on the proportion of oP dephosphorylated (kg/kg) in the small intestine (SI) and large intestine (LI) was determined as 0.26 - (0.015 × dietary Ca) and 0.69 - (0.059 × dietary Ca), respectively. The dephosphorylated oP in the LI was assumed to be indigestible and was excreted. Proportion of oP dephosphosphorylation (kg/kg) by microbial and plant phytase activity (FTU) in the stomach was estimated to be 0.56 × [1 - exp(-0.001 × FTU)] and 0.38 × [1 - exp(-0.002 × FTU)], respectively. Phosphorus digestibility (kg/kg) of NPP and dephosphorylated oP in the SI was assumed to be constant at 0.8. The model was used to predict P digestibility in 2 experiments by Stein et al. (2011) and Poulsen et al. (2010) and compare the predictions with experimental outcomes. The model successfully predicted the P digestibility to a range of dietary Ca concentrations and for 2 levels of supplementation with microbial phytase. However, the predictions overestimated P digestion systematically but always within a 10% margin of the observed values. The model could be a useful tool for formulating strategies to improve the efficiency of P digestion and reduce soluble P excretion in pigs.

The changes in behavior associated with a (subclinical) acute and a chronic health challenge were investigated to assess their potential value for the development of an early disease detection system in beef cattle. The hypothesis was that acute challenges would lead to acute but transient changes in behavior, whereas the converse would be the case during chronic challenges, with changes taking longer to develop, but being more persistent. For this purpose, Holstein-Friesian beef bulls were challenged either with a repeated lipopolysaccharide (LPS) intravenous bolus given at 3 increasing doses over the course of 5 d, or with a single dose of the abomasal parasite Ostertagia ostertagi, acting as models of acute and chronic challenge respectively. A third unchallenged group acted as controls. Fecal and blood samples were taken regularly and analyzed for fecal egg counts (FEC), pepsinogen concentration and LPS antibodies. A sensor was fitted to the front leg of each bull to record activity and posture. Video recordings were taken to monitor drinking and feeding behavior. Antibodies to LPS were detected only after the third LPS challenge. Fecal egg counts were detected 3 wk post infection, and pepsinogen increased roughly at the same time in parasitized bulls. Body weight of parasitized animals was reduced relative to controls after 17 d post infection (P < 0.001), whereas there was no difference in performance between the LPS and control animals (P > 0.05). Effects of LPS on behavior lasted only for a few hours, presenting themselves as reduction in activity approximately 10 h after the first challenge (P = 0.057). The clearest behavioral changes due to parasitism were on posture. Parasitized animals had less frequent (P = 0.003), but longer lying episodes (P = 0.038) than controls. Once established, these changes persisted for 30 d post infection. However, there was no treatment effect on overall activity, measured by the number of steps taken or on total lying time (P > 0.05). Frequency of feeding and drinking episodes and their duration were not affected by health challenge (P > 0.05); however there was an increase in average duration of feeding (P = 0.013) for the parasitized animals. Even though the parasite challenge had significant effects on several aspects of behavior, these may be considered too subtle to be useful indicators of disease; however when used with other measurements, they may prove helpful for the early detection of disease in beef cattle.

Effects of increased MP supply on the degree of periparturient relaxation of immunity (PPRI) in sheep may be dependent on quality of supplied MP. Here we tested the hypothesis that additional MP supply from rations based on xylose-treated soybean meal would be more effective than from rations based on faba beans in reducing the degree of PPRI, as indicated by nematode egg excretion. Twenty-four multiple-bearing ewes were trickle infected with Teladorsagia circumcincta larvae from d -56 to d 31 relative to start of lactation (d 0). From d -26 onwards, ewes were fed at either 0.8 (LP) or at 1.2 times their respective calculated MP requirements using either xylose-treated soybean (HPS) or faba beans (HPB). Litter size was adjusted to 2 lambs at parturition. Feeding treatments did not affect nematode egg excretion, ewe BW or BCS during late pregnancy (P > 0.10), but HPS and HPB ewes had reduced plasma pepsinogen concentrations (P = 0.003). During lactation, HPS and HPB feeding increased ewe BW gain (P < 0.001) and BCS (P = 0.017), and reduced plasma pepsinogen concentrations (P = 0.008) to the same extent, compared with LP feeding. However, only HPS feeding increased litter weight gain (P = 0.017) and reduced nematode egg excretion (P = 0.015), which were both similar between HPB and LP (P > 0.10). The results support the view that extra MP supply from xylose-treated soybean based rations is more effective in reducing parasitism than MP from faba bean-based rations, suggesting that protein source and/or quality are important factors to consider for the nutritional control of parasitism.

A mathematical model was developed to investigate the impact of level of Teladorsagia circumcincta larval pasture contamination and anthelmintic treatment on genetic parameter estimates for performance and resistance to parasites in sheep. Currently great variability is seen for published correlations between performance and resistance, with estimates appearing to vary with production environment. The model accounted for host genotype and parasitism in a population of lambs, incorporating heritable between-lamb variation in host-parasite interactions, with genetic independence of input growth and immunological variables. An epidemiological module was linked to the host-parasite interaction module via food intake (FI) to create a grazing scenario. The model was run for a population of lambs growing from 2 mo of age, grazing on pasture initially contaminated with 0, 1,000, 3,000, or 5,000 larvae/kg DM, and given either no anthelmintic treatment or drenched at 30-d intervals. The mean population values for FI and empty BW (EBW) decreased with increasing levels of initial larval contamination (IL(0)), with non-drenched lambs having a greater reduction than drenched ones. For non-drenched lambs the maximum mean population values for worm burden (WB) and fecal egg count (FEC) increased and occurred earlier for increasing IL(0), with values being similar for all IL(0) at the end of the simulation. Drenching was predicted to suppress WB and FEC, and cause reduced pasture contamination. The heritability of EBW for non-drenched lambs was predicted to be initially high (0.55) and decreased over time with increasing IL(0), whereas drenched lambs remained high throughout. The heritability of WB and FEC for all lambs was initially low (∼0.05) and increased with time to ∼0.25, with increasing IL(0) leading to this value being reached at faster rates. The genetic correlation between EBW and FEC was initially ∼-0.3. As time progressed the correlation tended towards 0, before becoming negative by the end of the simulation for non-drenched lambs, with increasing IL(0) leading to increasingly negative correlations. For drenched lambs, the correlation remained close to 0. This study highlights the impact of IL(0) and anthelmintic treatment on genetic parameters for resistance. Along with factors affecting performance penalties due to parasitism and time of reporting, the results give plausible causes for variation in genetic parameter estimates previously reported.

Forty-eight 4- to 5-yr-old Blackface x Bluefaced Leicester (Mule) ewes and their 24-d-old twin lambs were used to assess the effects of maternal protein nutrition and subsequent grazing on chicory (Cichorium intybus) on performance and parasitism. The experiment consisted of 2 grazing periods: safe pasture period and experimental pasture period. During an adaptation period of 66 d, ewes were infected through oral dosing with Teladorsagia circumcincta infective larvae (3 d per wk) and were supplemented with protein (HP) or not (LP) for the last 45 d of this period. At the end of this period, ewes and their lambs were turned out onto a parasitologically safe pasture; all ewes continued to be dosed with parasite (once a week), and HP ewes received protein supplementation for the first 35 d. Ewes and lambs grazed the safe pasture for an additional 43 d after termination of protein supplementation and of oral dosing with parasites. Ewes and their lambs were then moved onto newly established experimental pastures sown with chicory or grass/clover (Lolium perenne/Trifolium repens). During the safe pasture period, HP ewes had decreased fecal egg counts (FEC) compared with LP ewes, whereas HP lambs had temporarily less (P < 0.05) FEC, decreased (P < 0.001) plasma pepsinogen concentrations, and grew faster (P = 0.028) than LP lambs. Lambs grazing chicory had consistently less (P < 0.001) FEC and grew faster (P = 0.013) than lambs grazing grass/clover but had greater (P < 0.001) concentrations of pepsinogen. Pasture larvae counts were decreased (P = 0.07) for the chicory compared with the grass/clover plots. There were no interactions (P > 0.10) between maternal nutrition and grazed forage type on performance or parasitological measurements. Our results suggest that increased maternal protein nutrition and subsequent grazing of chicory independently improve lamb performance and reduce lamb parasitism.

The response to infection from porcine reproductive and respiratory syndrome virus (PRRSV) for 2 genetically diverse commercial pig lines was investigated. Seventy-two pigs from each line, aged 6 wk, were challenged with PRRSV VR-2385, and 66 litter-mates served as control. The clinical response to infection was monitored throughout the study and pigs were necropsied at 10 or 21 d postinfection. Previous analyses showed significant line differences in susceptibility to PRRSV infection. This study also revealed significant line differences in growth during infection. Line B, characterized by faster growth rate than line A in the absence of infection, suffered more severe clinical disease and greater reduction in BW growth after infection. Correlations between growth and disease-related traits were generally negative, albeit weak. Correlations were also weak among most clinical and pathological traits. Clinical disease traits such as respiratory scores and rectal temperatures were poor indicators of virus levels, pathological damage, or growth during PRRSV infection. Relationships between traits varied over time, indicating that different disease-related mechanisms may operate at different time scales and, therefore, that the time of assessing host responses may influence the conclusions drawn about biological significance. Three possible mechanisms underlying growth under PRRSV infection were proposed based on evidence from this and previous studies. It was concluded that a comprehensive framework describing the interaction between the biological mechanisms and the genetic influence on these would be desirable for achieving progress in the genetic control of this economically important disease.

Short and long-term effects of manipulating dietary CP content and diet quality in weaner diets on health and performance of pigs were investigated in a 2 x 2 factorial combination of CP inclusion (high-CP, 230 g of CP/kg vs. low-CP, 170 g of CP/kg) and diet quality (high-quality, cooked cereals, and animal protein vs. low-quality, raw cereals, and plant protein). Diets were fed ad libitum for 14 d postweaning to pigs weaned at 29.4+/-3.1 d of age and 9.9+/-1.0 kg of BW. From d 14 to slaughter at 104+/-3 kg, all pigs were fed the same series of standard commercial diets. There were 15 replicates per treatment in the weaner phase (<30 kg) and 5 replicates per treatment in the grower-finisher phase (>30 kg). High-quality diets promoted gut health as indicated by improved fecal lactobacilli to coliform ratio (P=0.002) and decreased fecal enterotoxigenic Escherichia coli counts on d 11 postweaning (P=0.028), reducing the risk of postweaning diarrhea and improving pig health from weaning to the end of the weaner phase. Reducing CP content had no effect on gut health. High-CP (P=0.053) and high-quality (P=0.025) diets independently increased ADG during the first 14 d postweaning compared with low-CP and low-quality diets, respectively. There were no interactions between dietary CP content and quality on any of the response criteria investigated. Despite differences in the immediate postweaning period, there was no effect of manipulating diet quality or CP content for 2 wk postweaning on lifetime performance with pigs reaching slaughter weight in 128+/-7 d. These results indicate that high-quality diets may protect pig gut health during the immediate postweaning period. However, it may be possible to use less expensive, decreased quality weaner diets without any adverse effects on long-term performance when weaning older, heavier pigs and where health status, environmental control, and stock management are all maintained to a high standard.

A reduction in food intake is a prominent feature of many infectious diseases. However, the underlying mechanisms of parasite-induced anorexia in sheep are poorly understood. Here, we tested the hypotheses (a) that the degree of parasite-induced anorexia in lambs is influenced by their growth potential and (b) that nematode infection results in elevated plasma leptin concentration in lambs. The hypotheses were tested with Suffolk x Greyface (S) and Scottish Black-face (B) lambs that are known to differ in their growth potential (S lambs are of greater growth potential than B lambs). During a primary parasite infection, 24 out of 48 lambs per breed were trickle-infected with 7,000 infective Teladorsagia circumcincta larvae per day, 3 d/wk, for a period of 12 wk (experiment I). The lambs were then dewormed, and after a 2-wk interval, half of the 24 lambs per breed that were previously infected were reinfected for another 12 wk with the same parasite and dose as used in the primary infection (experiment II). In both experiments, infected lambs were fed grass pellets for ad libitum intake, whereas noninfected lambs were fed grass pellets for either ad libitum or restricted intakes. The S lambs were more susceptible than B lambs to nematode infection, as judged from the differences in fecal egg counts (P = 0.007). Parasitized lambs of the more susceptible breed (S) showed anorexia [i.e., a decrease in intake of 13% compared with uninfected controls (P = 0.01)], whereas no significant reduction in food intake was observed in lambs of the more resistant breed (B). Reexposure to nematode infection of previously infected animals tended to result in renewed anorexia in S lambs but not in B lambs (P = 0.08) in a similar extent as during primary infection. Plasma leptin concentrations did not differ between ad libitum-fed infected and control lambs but were greater in infected than in noninfected lambs at a similar level of food intake during both the primary (P = 0.02) and the secondary parasitic infection (P = 0.004) in both breeds. The results show that leptin may be involved in the response of lambs to infection but that it is unlikely that leptin alone is responsible for the parasite-induced anorexia in lambs.

In a 1-yr experiment, nutritional treatments were used to produce different combinations of BW and BCS in lambs. The experiment served to quantify the effects of BW and BCS on ADFI by sheep. Ewe lambs (n = 78) were assigned to treatment groups that had ad libitum access to one feed at a time. Three feeds were used: a medium-quality chopped hay (L), a pelleted feed based on oat feed (M), and a pelleted feed based on barley (H). Three groups received only one of these feeds throughout. Two groups first received H and then were switched to M when they reached a BW of 45 or 65 kg. Two groups first received L and then were switched to M or H after reaching a BW of 45 kg. Three groups first received H or M but were switched to L after reaching a BW of 45, 65, or 95 kg. Daily feed intake, BW, and BCS were recorded, and ME content of the feeds was estimated in a separate digestibility experiment. The lambs consuming M ate more (P < 0.001) feed than lambs consuming H, but this had no significant effects on ME intake or gain in BW or BCS. Animals that had had access to L were lean for their BW when switched to H or M and showed compensatory intake and gain. Animals switched from M or H to L all lost BCS; BW change depended on the BW at the switch. The treatments produced different combinations of BW and BCS for animals with access to the same feed. The ADFI of a given feed varied systematically with BCS for animals of a given BW. The model ADFI = a x BW x [1 - (b x BCS)] gave a reasonable description of the data in all treatments. A model using BW, BCS, and their interaction gave a slightly better fit but explained little more of the variation in ADFI than the simpler model. The implications of the collected data are that BW alone is an insufficient descriptor of the animal to correctly predict feed intake and that intake predictions can be improved by taking BCS into account.

A general model is proposed for predicting the effects of subclinical pathogen challenges of different doses and virulence on the relative feed intake (RFI) of animals. The RFI is defined as the feed intake (FI, kg/d) of the animal challenged by a pathogen divided by its FI in the same state had it not been challenged. Actual FI can be predicted from the RFI and the animal's state. The RFI was assumed to be affected only when animals were naïve to a particular pathogen (i.e., had not previously experienced it) and when the challenge dose was above a predetermined threshold. The model is for the period from recognition of a pathogen through acquisition and subsequent expression of immunity. The way in which RFI changes with time is described by 5 main parameters and is based on data for RFI during different pathogen challenges of a range of hosts. Lag time (L, d) is the delay from a pathogen challenge until any effects on RFI are seen. Reduction time (R, d) describes the time it takes for the lowest value of RFI (lambda) to be achieved. The duration time (D, d) describes the time that lambda is maintained for, and rho (RFI/d) describes the rate of recovery of RFI until RFI = 1. There is no compensatory intake, and RFI is always < or = 1. The effects of host resistance on the values of the model parameters are proposed. Attempts were made to parameterize the model; when data were scarce, initial parameter values were derived on conceptual grounds. Predictions of the effects of pathogen dose, virulence, and host resistance are described and discussed. When comparing the responses in RFI for different genotypes, it is crucial to define the pathogen challenge (in terms of dose and virulence) and the degree of resistance of different hosts. Possible interactions between dose, virulence, and resistance were explored. Feed intake of healthy and challenged animals, at a time, may be different once the challenged animal has recovered (RFI = 1). The issue of reductions in FI during pathogen challenges is important for nutritionist and animal breeders. The large variation that has been observed for reductions in FI during pathogen challenges may be a viable point of selection. The points highlighted will aid selection strategies by quantifying the effects of pathogen dose and virulence, and time, on the FI of challenged animals. The proposed model may be integrated with other models of growth to predict animal performance during exposure to pathogens.

A simulation model that predicts the effect of the social, physical, and nutritional environments on pig food intake and performance was extended to deal with individual variation. The aim was to investigate the effect of between-animal variation on the performance of a population of growing pigs. Variation was generated in initial state, growth potential, and ability to cope when exposed to social "stressors" (EX). Variation in initial state is described by initial body weight (BW0), from which the chemical composition of the pig is calculated. Variation in growth potential is described by creating variation in the genetic growth descriptors. Variation in EX exists between genotypes, where it has been suggested that leaner, more modern genotype pigs tend to be less able to cope. It is expected that within a population or group that the social environment (i.e., position within the social hierarchy) also affects an individual's ability to cope. In the model, it is assumed that the larger, more dominant individuals are better able to cope when exposed to social stressors. Consequently, within a population, EX is correlated with body weight around the genotype mean. Model predictions showed that increasing the variation in BW0 and EX increased the variation in pig performance. This is an important practical consideration in commercial pig production, where the heterogeneity of the population at slaughter may affect the profitability of an enterprise. The way a stressor constrains performance determines whether the mean population response to a given stressor is the same as the average individual response. If all pigs in a group are affected at the same stressor intensity (e.g., all are either mixed or not), then the predicted average individual and mean population responses will be the same. If, however, the intensity of stressor at which performance becomes limiting differs between individuals (such as space allowance or temperature), differences between the individual and mean population responses will be predicted. Variation in the growth response of a population was determined to a greater extent by variation in EX and BW0 than by variation in growth potential, when pigs were housed in simulated conditions likely to be encountered in commercial environments. Consequently, decreasing the variation in initial body weight and improving ability of pigs to cope may be a better way of improving pig performance than selecting only for increased growth potential.

The influence of social stressors on pig performance, although undeniable, is frequently underestimated, and in pig growth modeling is generally ignored. The aims here were to quantify the effects of the main social stressors (i.e., group size, space allowance, feeder space allowance, and mixing) on the performance of growing pigs and to incorporate these relationships into a general growth simulation model. Effects of the individual stressors were described by conceptual equations derived on biological grounds. Parameter values were estimated from experimental data, while taking steps to avoid the problems of using a strictly empirical approach. It was assumed that social stress decreases the capacity of the animal to attain its potential. This is equivalent to lowering the maximum rate of daily gain (ADGp, kg/d). Because it is generally assumed that animals eat to attain their potential, a decrease in ADGp necessarily leads to a decrease in intake. Genetic variation among genotypes in their ability to cope with social stressors was accounted for by introducing an extra genetic parameter (EX) into the model. The value of EX adjusts both the intensity of stressor at which the animal becomes effectively stressed and the extent to which stress decreases performance and increases energy expenditure at a given stressor intensity. Rather than using an empirical adjustment to predict values for the model output variables, such as intake and gain, the chosen functional forms were integrated into a general growth model as mechanistic equations. This allowed the effects of interactions that exist between social stressors and the other variables, such as the genotype, feed composition, and environment on pig intake and growth, to be explored and, at least in principle, predicted. The adapted model is able to predict the performance of pigs differing in both the potential and ability to cope with environmental stressors when raised under given dietary, physical, and social environmental conditions. The social stressor equations developed here can be incorporated into other pig growth simulation models.