Body Composition Of Pigs Research Articles

Effects of sex on fat deposition through gut microbiota and short-chain fatty acids in weaned pigs

Nitrogen pollution resulting from excessive feed consumption poses a significant challenge for modern swine production. Precision nutrition technology seems to be an effective way to solve this problem; therefore, understanding the law of pig body composition deposition is a prerequisite. This study investigated the sex effects on growth performance, body composition, nutrient deposition, gut microbiota, and short-chain fatty acids (SCFA) in weaned piglets. Eighty weaned pigs were randomly allocated to 2 treatments according to the sex of pigs. An individual pig was considered as a treatment replicate. Six body weights (BW 5, 7, 11, 15, 20, and 25 kg) were chosen as experimental points; for each point 10 piglets close to the average BW (5 males and 5 females) were slaughtered, and there was one growth phase between each 2 BW points. Results indicated that the males had higher average daily gain (ADG) and average daily feed intake (ADFI) compared to the females (P < 0.05) at growth phases 15 to 20 kg BW and 20 to 25 kg BW. Meanwhile, males at 20 kg BW had higher body fat content than females (P < 0.10). Males showed a higher body fat (P < 0.05) deposition rate at phase 15 to 20 kg BW (P < 0.05) than females. For pigs at 20 kg BW, the relative abundance of RuminococcaceaeUCG-005, Clostridium, Christensenellaceae_R-7_group, and Peptostreptococcaceae was significantly increased in males (P < 0.05) but that of Bifidobacterium was decreased (P < 0.05). At 25 kg BW, the relative abundance of Ruminococcaceae_NK4A214_group, Fibrobacter, RuminococcaceaeUCG-009, Ralstonia, Klebsiel, and Christensenellaceae_R-7_group in males was higher when compared with females (P < 0.05). In terms of SCFA, females exhibited higher concentrations of propionate compared to males (P < 0.05). The results of the current study indicated that sex influenced fat deposition through changes in the composition of gut microbiota and the content of SCFA, which has significant implications for the realization of precision nutrition in modern swine production.

192 Effect of Dietary Anhydrous Calcium Chloride in Early and Late Finishing on Pig Performance and Body Composition

Abstract Understanding how to control pig growth is critical during market disruptions, including foreign animal disease and harvest facility shutdowns. In times of severe market disruptions, feeding acidogenic salts such as anhydrous calcium chloride to suppress appetite is an effective way to manage pig growth. Therefore, the aim of this study was to understand the impact of feeding calcium chloride during early and late growth stages on grow-finish growth and body composition of pigs. Barrows and gilts (n = 240; 52 ± 6.9 kg BW) were allotted by sex across 60 pens and to one of three treatments fed in 3 diet phases (Phase 1, d 1-28; Phase 2 d 28-56; Phase 3 d 57-87). Treatment included: 1) Control corn-soy diets in phases 1-3, 2) 3% CaCl2 intervention in phase 1, control diet fed in phases 2 and 3 (IP1), and 3) Control diet fed in phases 1 and 2, and 3% CaCl2 intervention in phase 3 (IP3). All diets were formulated to meet or exceed amino acid and energy requirements and pigs were fed ad libitum. Pig BW were recorded at the start and end of each phase, and pen feed disappearance was recorded to calculate pen ADG, ADFI, and G: F. Loin eye area and fat depth were measured using real-time ultrasound at the end of phases 1 and 3. Data were analyzed with pen as the experimental unit and treatment, gender, and their interaction as fixed effects. No noteworthy gender by diet interactions were demonstrated and only the diet treatment, overall performance, and ultrasound trait means are reported (Table 1). Compared with the Control and IP3, IP1 reduced ADFI and ADG by 42% and 60%, respectively, in phase 1 (P&amp;lt; 0.05). Feed efficiency, loin eye area, and fat depth were also reduced in the IP1 compared with the Control and IP3 pigs in phase 1 (P&amp;lt; 0.05). In phase 2, the IP1 pigs did not have a significant difference in feed intake and their ADG increased by 22% compared with the Control and IP3 pigs (P&amp;lt; 0.05) and therefore were more feed efficient. Implementation of CaCl2 in phase 3, the IP3 pigs reduced ADFI, ADG, and G: F compared with the control and IP1. Further, phase 3 loin eye area and fat depth were 13% and 17% less, respectively, in the IP3 pigs compared with the control. Overall, the IP3 treatment had the most severe reductions in ADG, ADFI, and feed efficiency (P&amp;lt; 0.05). Early intervention (IP1) also attenuated overall G: F, ADFI, and ADG compared with the Control (P&amp;lt; 0.05). These results demonstrate the efficacy of calcium chloride in attenuating pig feed intake and growth performance during early and late finishing.

Effects of lowering dietary protein content without or with increased protein-bound and feed-grade amino acids supply on growth performance, body composition, metabolism, and acute-phase protein of finishing pigs under daily cyclic heat stress.

This study investigated the effects of a low-protein diet with or without an increase in dietary protein and feed-grade amino acids (AAs) on the growth performance, body composition, metabolism, and serum acute-phase proteins of finishing pigs reared in thermoneutrality or cyclic heat stress conditions. A total of 90 gilts (67.7 ± 6.2 kg) were distributed in a 2 × 3 factorial arrangement (two ambient temperatures and three diets). Ambient temperatures (AT) were thermoneutral (TN, 22 °C for 24 h) and cyclic heat stress (CHS, 12 h to 35 °C and 12 h to 22 °C). The evaluated diets (D) were high crude protein (HP); low CP-free AA-supplemented diets (LPAAs); low CP-free AA-supplemented diets and digestible Lys level (+20%), and Lys:AA ratios above recommendations (LPAA+). The experimental period lasted 48 d (two experimental phases: days 0-27 and days 28-48, respectively). CHS pigs had higher skin temperature (P < 0.05) than TN pigs. Pigs in CHS had higher rectal temperature (P < 0.05) than TN pigs until day 38 but similar (P > 0.10) to TN pigs from 38 to 45 d. For the entire experiment, CHS pigs had lower (P < 0.05) final BW, average daily gain and daily feed intake, net energy intake, body lipid, bone mineral, lipid deposition, energy retention, Lys and CP intake, and nitrogen excretion than TN pigs. The level of CP intake impacted nitrogen excretion, nitrogen retention efficiency, and urea as pigs fed HP had the highest values, and pigs fed LPAA had the lowest values (P < 0.05). On day 27, CHS pigs had lower (P < 0.05) free triiodothyronine than TN pigs. LPAA+ pigs had lower (P < 0.05) insulin than LPAA. On day 48, CHS pigs had lower (P < 0.05) thyroxine, albumin, and lactate than TN pigs. On day 27, pigs fed LPAA+ had higher (P < 0.05) lactate than pigs fed HP or LPAA. Both AT and D were enough to stimulate the immune system as CHS pigs had lower (P < 0.05) transferrin and 23-kDa protein levels than TN pigs, and HP pigs had higher haptoglobin than LPAA on day 27. These results confirm the deleterious effects of high AT on performance, body composition, metabolism, and immune system stimulation in finishing pigs. These data also show that a diet with low levels of CP can be provided to pigs in CHS without affecting performance and body composition while reducing nitrogen excretion. However, the use of a diet with an AA level above the requirements obtained by increasing intact protein and free AA did not attenuate the impact of CHS on performance and body composition of pigs.

63 Effects of Dietary Calcium and Phosphorus Deficiency on Growth Performance and Subsequent Recovery of Bone Mineralization in Replacement Gilts

Abstract This study was performed to test the hypothesis that after a depletion period that renders replacement gilts more efficient in their use of calcium (Ca) and phosphorus (P), they can recover bone mineralization when fed a repletion diet. To this end, 24 gilts were fed according to a 2-phase feeding program (60–95 kg BW and 95–140 kg BW, respectively), corresponding to the period of depletion and repletion in Ca and P, respectively. The experimental diets for the first phase were a finisher control diet (D100; 2.1 g digestible P/kg) providing 100% of estimated Ca and P requirements or a finisher low-P diet (D60; 1.2 g digestible P/kg) providing 60% of estimated Ca and P requirements. In the second phase, one-half of the gilts from each finisher diet were randomly assigned to either a control (R100) diet or a high-P diet (R160; 3.5 g digestible P/kg) according to a 2 × 2 factorial design, resulting in 4 treatments: D60R100, D60R160, D100R100 and D100R160. Whole-body bone mineral content (BMC) and body composition of pigs were measured on each gilt at 2-week intervals by dual energy X-ray absorptiometry. Diets did not influence the growth performance throughout the experiment. At 95 kg, gilts fed D60 had reduced BMC and BMD (-9% vs D100; P &amp;lt; 0.001). At 140 kg, no significant effect of depletion diets was observed on BMC. These results show the high potential to limit dietary digestible P concentration during the growing period without causing any detrimental effects to gilts at mating, and they confirm the ability of replacement gilts to recover their BMC at 140 kg BW by increasing BMC deposition and their dietary Ca and P efficiency. Finally, high-digestible P content from 95-140 kg BW allowed gilts to increase BMC further, but required the use of dietary phosphates.

Relationship between energy intake and growth performance and body composition in pigs selected for low backfat thickness.

Genetic selection of pigs over recent decades has sought to reduce carcass fat content to meet consumer demands for lean meat in many countries (e.g., Australia). Due to the impacts of genetic changes, it is unknown whether the carcass fat measures are still responsive to energy intake. Thus, the present experiment aimed to quantify the relationship between tissue composition and dietary energy intake in finisher pigs selected for low carcass backfat. Intact male and female pigs (n = 56 for each sex; Primegro Genetics, Corowa, NSW, Australia) were fed seven different amounts of an amino acid adequate wheat-based diet containing 14.3 MJ digestible energy (DE)/kg to provide the following daily DE intakes- 25.8, 29.0, 32.6, 35.3, 38.5, 41.5, and 44.2 (ad libitum) MJ DE/d for males, and 25.8, 28.9, 32.0, 35.6, 38.3, 40.9, and 44.5 (ad libitum) MJ DE/d for females between 60 and 108 kg live weight. Body composition of anesthetized pigs was measured using the dual energy X-ray absorptiometry (DXA) method when individual pigs reached 108 kg, and protein, fat, and ash deposition rates were calculated. Pigs were slaughtered on the second day post-DXA scan for carcass backfat measurement. The results showed that the carcass backfat thickness (standardized at 83.7 kg carcass) increased by 0.125 mm for every MJ increase in daily DE intake in male pigs (P = 0.004; R2 = 0.130), but carcass backfat of female pigs (standardized at 85.1 kg carcass) was not responsive to daily DE intake. Whole-body fat composition and fat deposition rate increased linearly (both P < 0.01) in male pigs but quadratically (both P < 0.01) in female pigs in response to DE intake. Every MJ increase of daily DE intake increased the rate of daily protein deposition by 3.8 g in intact male pigs (P < 0.001; R2 = 0.781) and by 2.5 g in female pigs (P < 0.001; R2 = 0.643). In conclusion, the selection for low backfat thickness over the last two decades has altered the response of fat deposition and backfat thickness to energy intake, particularly in female pigs. Despite this change, the linear relationship between DE intake and protein deposition rate was maintained in these modern genetics.

Accuracy of predicting chemical body composition of growing pigs using dual-energy X-ray absorptiometry

Studies in animal science assessing nutrient and energy efficiency or determining nutrient requirements benefit from gathering exact measurements of body composition or body nutrient contents. Those are acquired by standardized dissection or by grinding the body followed by wet chemical analysis, respectively. The two methods do not result in the same type of information, but both are destructive. Harnessing human medical imaging techniques for animal science can enable repeated measurements of individuals over time and reduce the number of individuals required for research. Among imaging techniques, dual-energy X-ray absorptiometry (DXA) is particularly promising. However, the measurements obtained with DXA do not perfectly match dissections or chemical analyses, requiring the adjustment of the DXA via calibration equations. Several calibration regressions have been published, but comparative studies of those regression equations and whether they are applicable to different data sets are pending. Thus, it is currently not clear whether existing regression equations can be directly used to convert DXA measurements into chemical values or whether each individual DXA device will require its own calibration. Our study builds prediction equations that relate body composition to the content of single nutrients in growing entire male pigs (BW range 20–100 kg) as determined by both DXA and chemical analyses, with R2 ranging between 0.89 for ash and 0.99 for water and CP. Moreover, we show that the chemical composition of the empty body can be satisfactorily determined by DXA scans of carcasses, with the prediction error ranging between 4.3% for CP and 12.6% for ash. Finally, we compare existing prediction equations for pigs of a similar range of BWs with the equations derived from our DXA measurements and evaluate their fit with our chemical analysis data. We found that existing equations for absolute contents that were built using the same DXA beam technology predicted our data more precisely than equations based on different technologies and percentages of fat and lean mass. This indicates that the creation of generic regression equations that yield reliable estimates of body composition in pigs of different growth stages, sexes and genetic breeds could be achievable in the near future. DXA may be a promising tool for high-throughput phenotyping for genetic studies, because it efficiently measures body composition in a large number and wide array of animals.

PSVI-13 Sequential feeding with diets varying in amino acid content improves body composition in growing-finishing pigs

Abstract This study evaluated the effect of conventional (CONV) and sequential feeding (SEQ) programs with diets varying in amino acid content over the day on body composition in growing-finishing pig. Sixty-eight 25-kg (±2.04) BW barrows were assigned to the following feeding programs: 1) CONV in which pigs received 100% of standardized ileal digestible (SID) AA recommendations for the entire day; 2) SEQ providing 80% SID AA recommendations from 2400 to 1159 h and 120% from 1200 to 2359 h (SEQ80-120); 3) SEQ providing 70% SID AA recommendations from 2400 to 1159 h and 130% from 1200 to 2359 h (SEQ70-130); and 4) SEQ providing 60% SID AA recommendations from 2400 to 1159 h and 140% from 1200 to 2359 h (SEQ60-140). The experimental period lasted 82 days. At days 0, 28, 54 and 82 body lean mass, fat and minerals were measured using a dual energy X-ray absorptiometry (DXA). Pigs fed SEQ80-120 had body composition variables similar to CONV pigs (P &amp;gt;0.05). Whereas, pigs fed SEQ70-130 had greater (P&amp;lt; 0.05) body fat mass (5.27 vs 4.48 kg), bone mineral content (0.656 vs 0.605 kg), fat mass gain (0.100 vs 0.073 kg/d) and bone mineral gain (6.92 vs 5.16 g/d) than CONV pigs during phase 1. Still during phase 1, SEQ60-140 fed pigs had greater (P&amp;lt; 0.05) bone mineral content (0.655 vs 0.605 kg), lean mass gain (0.436 vs 0.374 kg/d) and bone mineral gain (7.48 vs 5.16 g/d) than CONV pigs. During phase 3, bone mineral content was higher (P&amp;lt; 0.05) for SEQ70-130 than CONV (1.408 vs 1.269 kg). During the entire experimental period, body composition variables were not affected by SEQ (P &amp;gt;0.05). According to our results, sequential feeding program improves body composition of pigs at the beginning of the growth period.

Computed tomography evaluation of gilt growth performance and carcass quality under feeding restrictions and compensatory growth effects on the sensory quality of pork

Restricted feed can affect the body composition of pigs. Body composition can be studied non-destructively in live pigs using computed tomography (CT). The objective was to investigate the effect of different feeding restriction strategies on the productive and carcass quality parameters of gilts during growth via CT images and the effects of such strategies on meat quality, sensory properties and consumer preferences. Moreover, we sought to determine whether CT is a suitable tool for this purpose in this type of study. Thus, 36 Pietrain x (Large White x Landrace) gilts were assigned to the following three feeding strategies: 1) ad libitum feeding (AL) during all fattening periods (AL-AL); 2) AL feeding between 30 and 70 kg target body weight (TBW) followed by restriction (84% of AL) until 120 kg TBW (AL-RV); and 3) restriction feeding (78% of AL) between 30 and 70 kg TBW followed by AL until 120 kg TBW (RV-AL). When the pigs reached 30, 70, 100 and 120 kg, they were CT scanned to obtain the carcass composition parameters. At 120 kg TBW, the pigs were slaughtered, and the carcass and meat quality was determined. The loins were collected for trained panel evaluation and consumer tests. The panellists evaluated the odour, flavour and texture attributes of cooked loins. A total of 120 consumers scored the overall acceptability, tenderness, odour and flavour. The results showed a decrease of 76% and 80% in the average daily gain and average daily feed intake during the restriction period compared with the ad libitum in the growth phase, respectively, and a decrease of 89% and 87% in these parameters during the fattening phase, respectively. A restriction reduces the body fat content during the period of the restriction. Differences in the carcass and cut composition and meat quality were not observed at the end of the experiment among the treatments. Regarding sensory quality, meat from the animals in the AL-AL treatment was tougher than that from animals in the RV-AL and AL-RV treatments. Nevertheless, these differences were not detected by consumers, who did not provide significantly different scores for acceptability. Thus, when preparing feeding strategies, these results should be considered to optimize costs and increase benefits. Furthermore, computed tomography represents a non-destructive technology suitable for determining carcass composition before slaughter.

PSIII-7 Production trait differences between show pig and commerical genetic lines

Abstract The objective was to compare growth and body composition of pigs sired by boars from the show pig industry to those sired by modern commercial genetic lines. Data included one group of 174 male pigs from 16 sires and 50 dams. Pigs were sired by Large White (LW) show pig sires (SHOW) or one of two maternal LW commercial genetic lines (W or P). Dams of all pigs evaluated were from line P. Pigs were weaned at 27 d of age and placed into a mechanically ventilated nursery (0.23 m2 per pig). After 35 d in the nursery, pigs moved to a naturally ventilated finisher (0.74 m2 per pig) with fully slatted floors. Weight, 10th rib backfat, and loin eye area (LEA) were collected at 156 d of age (backfat and LEA adjusted to 114 kg). Data was analyzed using PROC GLM with a fixed effect of genetic line and covariates of weaning age and birth weight. A one day increase in weaning age increased (P &lt; 0.01) 156 d weight by 658 g. Nursery average daily gain (ADG) was greater (P &lt; 0.01) for pigs sired by SHOW and W when compared to P (414 and 397 vs. 351 g, respectively) yet finishing ADG did not differ (P &gt; 0.05) (821 and 817 vs. 797 g, respectively). Backfat was thicker (P &lt; 0.01) for SHOW when compared to W or P (16.7 vs. 14.7 and 14.7 mm, respectively) and LEA was larger (P &lt; 0.05) for SHOW when compared to W or P (47.3 vs. 44.8 and 44.0 cm2, respectively). Finishing lean gain per day was greater (P &lt; 0.05) for SHOW and W when compared to P (323 and 322 vs. 309 g per d, respectively). Results suggest pigs sired by LW SHOW are fatter, heavier muscled, and have comparable lean growth to those sired by commercial LW genetic lines.

Imaging technologies to study the composition of live pigs: A review

Image techniques are increasingly being applied to livestock animals. This paper overviews recent advances in image processing analysis for live pigs, including ultrasound, visual image analysis by monitoring, dual-energy X-ray absorptiometry, magnetic resonance imaging and computed tomography. The methodology for live pigs evaluation, advantages and disadvantages of different devices, the variables and measurements analysed, the predictions obtained using these measurements and their accuracy are discussed in the present paper. Utilities of these technologies for livestock purposes are also reviewed. Computed tomography and magnetic resonance imaging yield useful results for the estimation of the amount of fat and lean mass either in live pigs or in carcasses. Ultrasound is not sufficiently accurate when high precision in estimating pig body composition is necessary but can provide useful information in agriculture to classify pigs for breeding purposes or before slaughter. Improvements in factors, such as the speed of scanning, cost and image accuracy and processing, would advance the application of image processing technologies in livestock animals.

Effects of in utero heat stress on postnatal body composition in pigs: I. Growing phase.

Environmentally induced heat stress (HS) negatively influences production variables in agriculturally important species. However, the extent to which HS experienced in utero affects nutrient partitioning during the rapid lean tissue accretion phase of postnatal growth is unknown. Study objectives were to compare future whole-body tissue accretion rates in pigs exposed to differing in utero and postnatal thermal environments when lean tissue deposition is likely maximized. Pregnant sows were exposed to thermoneutral (TN; cyclical 15°C nighttime and 22°C daytime; n = 9) or HS (cyclical 27°C nighttime and 37°C daytime; n = 12) conditions during their entire gestation. Twenty-four offspring from in utero TN (IUTN; n = 6 gilts and 6 barrows; 30.8 ± 0.2 kg BW) and in utero HS (IUHS; n = 6 gilts and 6 barrows; 30.3 ± 0.2 kg BW) were euthanized as an initial slaughter group (ISG). Following the ISG, 48 pigs from IUTN (n = 12 gilts and 12 barrows; 34.1 ± 0.5 kg BW) and IUHS (n = 12 gilts and 12 barrows; 33.3 ± 0.3 kg BW) were exposed to constant HS (34.1 ± 2.4°C) or TN (21.5 ± 2.0°C) conditions until they reached 61.5 ± 0.8 kg BW, at which point they were sacrificed and their whole-body composition was determined. Homogenized carcasses were analyzed for N, crude fat, ash, water, and GE content. Data were analyzed using PROC MIXED in SAS 9.3. Rectal temperature and respiration rate increased (P < 0.01) during postnatal HS compared to TN (39.4 vs. 39.0°C and 94 vs. 49 breaths per minute, respectively). Regardless of in utero environment, postnatal HS reduced (P < 0.01) feed intake (2.06 vs. 2.37 kg/d) and ADG (0.86 vs. 0.98 kg/d) compared to TN conditions. Postnatal HS did not alter water, protein, and ash accretion rates but reduced lipid accretion rates (198 vs. 232 g/d; P < 0.04) compared to TN-reared pigs. In utero environment had no effect on future tissue deposition rates; however, IUHS pigs from the ISG had reduced liver weight (P < 0.04; 17.9%) compared to IUTN controls. In summary, postnatal HS reduced adipose tissue accretion rates, but IUHS did not appear to impact either lean or adipose tissue accretion during this specific growth phase.

Effects of in utero heat stress on postnatal body composition in pigs: II. Finishing phase.

The detrimental effects of heat stress (HS) on animal productivity have been well documented. However, whether in utero HS interacts with a future thermal insult to alter tissue deposition during the finishing phase of pig growth is unknown. Study objectives were to compare the subsequent rate and quantity of whole-body tissue accretion in pigs exposed to differing in utero and postnatal thermal environments. Pregnant sows were exposed to thermoneutral (TN; cyclical 15°C nighttime and 22°C daytime; n = 9) or HS (cyclical 27°C nighttime and 37°C daytime; n = 11) conditions during their entire gestation. Twenty-four offspring from in utero TN (IUTN; n = 6 gilts and 6 barrows; 62.4 ± 0.7 kg BW) and in utero HS (IUHS; n = 6 gilts and 6 barrows; 61.9 ± 0.8 kg BW) were euthanized as part of an initial slaughter group (ISG). After the ISG, 48 pigs from IUTN (n = 12 gilts and 12 barrows; 66.1 ± 1.0 kg BW) and IUHS (n = 12 gilts and 12 barrows; 63.4 ± 0.7 kg BW) were exposed to constant HS (34.4 ± 1.8°C) or TN (22.7 ± 2.5°C) conditions until they reached 80.5 ± 1.5 kg BW, at which point they were sacrificed and their whole-body composition was determined. Homogenized carcasses were analyzed for N, crude fat, ash, water, and GE content. Data were analyzed using PROC MIXED in SAS 9.3. Rectal temperature and respiration rate increased during postnatal HS compared to TN (39.6 vs. 39.3°C and 92 vs. 58 breaths per minute, respectively; P < 0.01). Postnatal HS decreased (P < 0.01) feed intake (2.13 vs. 2.65 kg/d) and ADG (0.70 vs. 0.94 kg/d) compared to TN conditions, but neither variable was influenced by in utero environment. Whole-body protein and lipid accretion rates were reduced in HS pigs compared to TN controls (126 vs. 164 g/d and 218 vs. 294 g/d, respectively; P < 0.04). Independent of postnatal environments, IUHS reduced future protein accretion rates (16%; P < 0.01) and tended to increase lipid accretion rates (292 vs. 220 g/d; P < 0.07) compared to IUTN controls. The ratio of lipid to protein accretion rates increased (95%; P < 0.01) in IUHS pigs compared to IUTN controls. In summary, the future hierarchy of tissue accretion is altered by IUHS, and this modified nutrient partitioning favors adipose deposition at the expense of skeletal muscle during this specific phase of growth.

Use of magnetic resonance imaging to predict the body composition of pigs in vivo

The objective of the study was to evaluate whether magnetic resonance imaging (MRI) offers the opportunity to reliably analyze body composition of pigs in vivo. Therefore, the relation between areas of loin eye muscle and its back fat based on MRI images were used to predict body composition values measured by dual energy X-ray absorptiometry (DXA). During the study, a total of 77 pigs were studied by MRI and DXA, with a BW ranging between 42 and 102 kg. The pigs originated from different extensive or conventional breeds or crossbreds such as Cerdo Iberico, Duroc, German Landrace, German Large White, Hampshire and Pietrain. A Siemens Magnetom Open was used for MRI in the thorax region between 13th and 14th vertebrae in order to measure the loin eye area (MRI-LA) and the above back fat area (MRI-FA) of both body sides, whereas a whole body scan was performed by DXA with a GE Lunar DPX-IQ in order to measure the amount and percentage of fat tissue (DXA-FM; DXA-%FM) and lean tissue mass (DXA-LM; DXA-%LM). A linear single regression analysis was performed to quantify the linear relationships between MRI- and DXA-derived traits. In addition, a stepwise regression procedure was carried out to calculate (multiple) regression equations between MRI and DXA variables (including BW). Single regression analyses showed high relationships between DXA-%FM and MRI-FA (R2 = 0.89, √MSE = 2.39%), DXA-FM and MRI-FA (R2 = 0.82, √MSE = 2757 g) and DXA-LM and MRI-LA (R2 = 0.82, √MSE = 4018 g). Only DXA-%LM and MRI-LA did not show any relationship (R2 = 0). As a result of the multiple regression analysis, DXA-LM and DXA-FM were both highly related to MRI-LA, MRI-FA and BW (R2 = 0.96; √MSE = 1784 g, and R2 = 0.95, √MSE = 1496 g). Therefore, it can be concluded that the use of MRI-derived images provides exact information about important ‘carcass-traits’ in pigs and may be used to reliably predict the body composition in vivo.

Chemical composition of growing pigs and its relationship with body tissue composition assessed by X-ray-computed tomography1,2

Ninety hybrid (mainly Large White × Landrace) pigs from 2 experimental replicates were used to study the potential use of computed tomography (CT) as a nondestructive technology for estimating the chemical body composition of growing pigs. Body tissue components (lean, fat, and bone) of 6 live pigs from each sex (boars, gilts, and barrows) were assessed by CT imaging before slaughter at approximately 30, 60, 90, 120, and 150 kg of BW. After slaughter, the empty body components were ground and frozen until analyzed for protein, lipid, ash, and moisture content. Several growth functions were evaluated and the allometric function (Y = aBW(b)), which was evaluated as log(10)chemical component weight = b(0) + b(1)log(10)BW, provided the best fit to the data. For each sex, the allometric coefficient (b(1)) for protein (0.92 to 0.99) was close to but less than 1; for ash (1.03 to 1.12), it was close to but greater than 1; for moisture (0.82 to 0.86), it was less than 1, and for lipid (1.61 to 1.71), it was greater than 1. Deposition rates (change in component weight per unit change in BW) for each chemical component were predicted using derivatives of the function. The mean deposition rates for protein and lipid were 0.141 and 0.286 kg/kg of BW gain, respectively. The deposition rate for protein was generally stable across different BW, whereas that for lipid increased as BW increased. In addition, linear, quadratic, exponential, and logistic functions were fitted to the data to study the relationship between the CT data and chemical components. The linear function was assessed to be the best equation, based on the Bayesian information criterion. The prediction equation for protein (kg) = -1.64 + 0.28 × CT lean (kg), and for lipid (kg) = -0.69 + 1.09 × CT fat (kg), had R(2) values of 0.924 and 0.987, respectively. Sex had no effect (P > 0.05) on the prediction of protein and lipid. The effect of BW was not significant (P > 0.05) for the prediction of lipid, but it was significant (P > 0 0.05) for the prediction of protein. However, the addition of BW to the base prediction equation for protein resulted in an increase of only 0.013 in the R(2) value. It was concluded from this study that CT scanning has great potential as a nondestructive technology for estimating the physical and chemical body composition of pigs. Additional research is required to validate the utility and accuracy of the prediction equations.

Epistatic quantitative trait loci affecting chemical body composition and deposition as well as feed intake and feed efficiency throughout the entire growth period of pigs

Numerous quantitative trait loci (QTL) have been identified for growth and feed intake in pigs, however, there are currently no reports of interactions between QTL (epistasis) for these traits at different stages of growth. A genomic scan for epistatic QTL was conducted on animals from a three generation full-sib population, created by crossing Pietrain sires with a crossbred dam line. All types of two-locus interactions were fitted in the model using Cockerham's decomposition, by regressing on a linear combination of the individual QTL origin probabilities. This study is the first to report epistatic QTL for growth, feed intake and chemical body composition in pigs. Eighteen significant epistatic QTL pairs were identified, seven affecting growth, six affecting feed intake or food conversion ratio, and five affecting chemical body composition. Most interacting QTL resided on different chromosomes; only two were located on the same chromosome. The identified QTL pairs explained substantial proportions of the phenotypic variance, from 5% to 10.3%. All types of digenic epistatic effects were identified with the additive-by-additive effect being the most prevalent. These findings suggest that epistasis is important in the genomic regulation of growth, feed intake and chemical body composition. Furthermore, interactions occur between different pairs of epistatic QTL for the same trait depending on the growth stage, increasing the complexity of genomic networks. This agrees with studies on gene expression levels which showed that those are time and tissue dependent.

Epistatic analysis of carcass characteristics in pigs reveals genomic interactions between quantitative trait loci attributable to additive and dominance genetic effects1

The present study focused on the identification of epistatic QTL pairs for body composition traits (carcass cut, lean tissue, and fat tissue weights) measured at slaughter weight (140 kg of BW) in a 3-generation full-sib population developed by crossing Pietrain sires with a crossbred dam line. Depending on the trait, phenotypic observations were available for 306 to 315 F(2) animals. For the QTL analysis, 386 animals were genotyped for 88 molecular markers covering chromosomes SSC1, SSC2, SSC4, SSC6, SSC7, SSC8, SSC9, SSC10, SSC13, and SSC14. In total, 23 significant epistatic QTL pairs were identified, with the additive x additive genetic interaction being the most prevalent. Epistatic QTL were identified across all chromosomes except for SSC13, and epistatic QTL pairs accounted for between 5.8 and 10.2% of the phenotypic variance. Seven epistatic QTL pairs were between QTL that resided on the same chromosome, and 16 were between QTL that resided on different chromosomes. Sus scrofa chromosome 1, SSC2, SSC4, SSC6, SSC8, and SSC9 harbored the greatest number of epistatic QTL. The epistatic QTL pair with the greatest effect was for the entire loin weight between 2 locations on SSC7, explaining 10.2% of the phenotypic variance. Epistatic associations were identified between regions of the genome that contain the IGF-2 or melanocortin-4 receptor genes, with QTL residing in other genomic locations. Quantitative trait loci in the region of the melanocortin-4 receptor gene and on SSC7 showed significant positive dominance effects for entire belly weight, which were offset by negative dominance x dominance interactions between these QTL. In contrast, the QTL in the region of the IGF-2 gene showed significant negative dominance effects for entire ham weight, which were largely overcompensated for by positive additive x dominance genetic effects with a QTL on SSC9. The study shows that epistasis is of great importance for the genomic regulation of body composition in pigs and contributes substantially to the variation in complex traits.

Early weaning has minimal effects on lifetime growth performance and body composition of pigs

Two hundred and forty pigs (120 entire boars and 120 gilts) were selected in three replicates of 40 boars and 40 gilts and housed in pens of 20 pigs of the same sex. Pigs were allocated to a 2 by 2 factorial experiment, with the respective factors being sex (entire male or female) and age at weaning (13 or 21 days). Pigs within each replicate were weaned on the same day, with the pigs’ farrowing date differing by ~8 days for the two weaning ages. Pigs were offered ad libitum access to feed for the entire experimental period. Eight randomly selected pigs from each pen were tagged as focus animals. These animals underwent dual energy X-ray absorptiometry (DXA) scanning six times from weaning through to slaughter to measure changes in body composition. The animals weaned at 13 days of age were lighter at weaning (4.68 ± 1.16 and 6.84 ± 1.34 kg, respectively, for the animals weaned at 13 and 21 days, P &lt; 0.001). During the first 4 days after weaning pigs weaned at 21 days of age consumed more feed (72.1 v. 30.9 g/day, P &lt; 0.001) and gained faster (35.0 v. –63.0 g/day, P = 0.042) than those weaned at 13 days. The pigs weaned at 13 days did, however, ‘catch up’ to be the same weight as those weaned at 21 days by 53 days of age (17.4 and 17.8 kg, respectively, P = 0.33). Daily gain from birth to 146 days of age did not differ across treatments (610, 597, 640, 657 g/day, respectively, for the gilts weaned at 13 days, gilts weaned at 21 days, boars weaned at 13 days and boars weaned at 21 days, P = 0.31). DXA analyses indicated that the animals weaned at 13 days had a greater percentage of lean tissue at 119 days of age (78.4 and 76.8%, respectively, P = 0.039) although this was not maintained through to slaughter. There were no treatment effects on the percentage of adipose tissue from 90 to 146 days of age, although the DXA estimated adipose tissue mass was greater at 146 days of age in the animals weaned at 21 days (13.8 and 15.2 kg, respectively, for the animals weaned at 13 and 21 days of age, P = 0.023, s.e.d. 0.60). These data suggest that weaning age predominately influences growth immediately after weaning, and does not have a major influence on lifetime growth performance or body composition at commercial slaughter weights.

Relationships among dual-energy X-ray absorptiometry, bioelectrical impedance and ultrasound measurements of body composition of swine

Abstract. In three separate studies (156 pigs total), dual-energy X-ray absorptiometry (DXA), bioelectrical impedance (BIA) and ultrasound were compared as methods for measuring live body composition of pigs at 60 and 100-110 kg BWt. DXA measured total body fat and lean content, BIA measurements of resistance (Rs) and reactance (Xc) were used to calculate total body lean mass and ultrasound measurements of backfat (BF) depth and longissimus muscle area (LMA) were used to calculate total carcass lean mass. Following the 100–110 kg measurements, the pigs were slaughtered and the half-carcass analyzed chemically for fat and water content. At 110 kg both DXA and ultrasound measurements were significantly correlated with the percentages of carcass fat and water, although correlations were higher for DXA. The correlations between DXA and BF measurements were higher at 110 kg than at 60 kg, whereas they were lower for DXA and LMA. For pigs measured at 100 kg there were high correlations between the DXA values and the BIA estimates for both percentage of fat-free lean mass (FFM %) and FFM kg. Furthermore, the correlations between the BIA estimates of FFM and carcass fat and water content were similar to those for DXA and the same carcass values. This study also provided a side-by-side comparison of the BIA and ultrasound lean measurements relative to DXA and carcass composition. The BIA lean measurement correlated more highly with both DXA and carcass composition than did the ultrasound lean measurement.

Novel epistatic QTL for chemical body composition and accretion as well as feed efficiency in pigs

Most quantitative trait loci (QTL) studies have focussed on the identification of individual QTL effects (additive, dominance and imprinting) in the absence of interactions (epistasis). There are numerous reports in the literature for QTL associated with growth and body composition of pigs, however much less effort has focussed around the identification of epistatic QTL for these traits. Growth and body composition of pigs are probably influenced by numerous QTL located throughout the genome as well as interactions between QTL. Therefore the objective of this study was to investigate the contribution of epistasis to the genomic regulation of growth and body composition of pigs.

The effects of sire genotype and the porcine circovirus type 2 vaccine on the growth performance of pigs from weaning to slaughter

Crossbreeding is common practice in commercial pig production as one way to increase lean growth and improve meat quality (Visscher et al., 2000). Reducing disease is another way to help improve growth rate in pigs. Porcine circovirus type 2 (PCV2) has devastated the pig industry in recent years. PCV2 infection increases mortality and reduces growth rate as it acts as an immunosuppressant thereby making pigs more susceptible to co-infections (Kixmöller et al 2008). Keeping disease at low levels has been achieved by improving husbandry standards, biosecurity, minimising presence of other pathogens and use of antibiotics. However vaccines against PVC2 are now available. The aim of this study was to investigate the effects of sire genotype and PCV2 vaccine on growth performance and body composition of pigs.