P2 Backfat Research Articles

Intramuscular fat % in the loin of Australian pork demonstrates a stronger relationship with computed tomography lean and fat % than abattoir measures of P2 and lean.

Intramuscular fat (IMF) % is an important measure of pork eating quality, with reduced IMF % linked to the selection of pigs with low backfat P2 thickness and more muscular genotypes over several decades. This experiment tested the association of IMF % from the M. longissimus thoracis et lumborum of 345 pigs at three abattoirs (Sites) with computed tomography (CT) determined carcass composition (% lean or fat), accredited abattoir measures of P2 backfat (mm) (Hennessy Grading Probe, AutoFom III and PorkScan Lite) and the lean % output from abattoir devices (Hennessy Grading Probe, AutoFom III and PorkScan Plus). There was a negative relationship between carcass CT lean % with IMF % at all Sites (P < 0.05), with the strength of this relationship varying between Sites. The strongest relationship was demonstrated at Site 1 (R2 0.30, RMSE 0.59), and across a 4 standard deviation range in the carcass lean % at each Site, resulted in a decrease in loin IMF % of 1.56, 0.44 and 0.80. There was a positive relationship of carcass CT fat % with IMF %, with similar, albeit slightly stronger relationship to IMF than with CT lean %. In contrast, only one of the three Sites with an accredited P2 measurement device demonstrated a significant association (P < 0.05) with IMF %. This is the first time the associations of IMF % with carcass CT composition has been assessed alongside that of P2 backfat measures from commercially deployed abattoir devices. Given P2 backfat is the key industry measure on which carcass value is determined in Australia, this experiment demonstrates the limitations that P2 has in measuring and monitoring the associations of carcass lean and fat % with IMF. Ideally, an independent measure of IMF % would allow for independent selection for lean % and IMF %, however there is currently no commercial device that can measure pork IMF %.

Effects of maternal contact and positive human contact during lactation on pork quality: Positive human contact to piglets during lactation improves pork loin muscle pH

Enhancing stress resilience through the early life period in pigs could potentially improve pork quality. It was hypothesised that pigs receiving maternal contact or positive human contact during lactation would have improved carcass and pork quality. Seventy-nine mixed-sex pigs were selected from a 2 × 2 factorial randomised block design for treatments maternal contact (MC+) / reduced maternal contact (MC-); and positive human contact (HC+) / control (HC-). Modified farrowing crates were utilised to reduce maternal contact (MC-). Litters in the HC+ treatment received five minutes of daily positive human interaction (stroking). Treatments ceased at 22 days of age (weaning) and pigs were slaughtered after 21 weeks of age. The m. longissimus thoracis et lumborum pH was higher in HC+ than HC- pigs (P < 0.05) during chilling, from 90 min post slaughter. No HC effects (P > 0.05) were observed for cortisol or haptoglobin concentration, hot carcass weight, P2 backfat, carcass scratches, colour, drip loss, cook loss and shear force. MC+ tended (P < 0.086) to increase carcass weight, P2 and carcass scratch score compared to MC-, but no further impacts were observed. The impact of positive human contact during early life was observed 20+ weeks after treatment with reduced pH decline, potentially indicating a reduction in pre-slaughter stress, however there were no further impacts on pork quality. There is evidence that maternal contact is important for lifetime growth performance of pigs but the impacts on stress resilience are less apparent.

Growth Performance, Meat Quality, and Lipid Oxidation in Pigs’ Fed Diets Containing Grape Pomace

Grape pomace is a winery byproduct that is rich in polyphenols with antioxidant capacity. This study investigated the effect of 0, 5, and 10% inclusion of dehydrated grape pomace (DGP) in finishing pig diets on the growth performance, carcass traits, fatty acid profile, fresh meat quality, and fat stability of a local pig genotype. A total of 36 pigs, 18 barrows, and 18 gilts (83.23 ± 6.03 kg and 132.1 ± 5.6 days old) were allotted in a randomized block design considering the initial weight (block) within sex, with six replicates of each sex per treatment. Including DGP in the diets did not affect daily weight gain or the feed-to-gain ratio; however, daily feed intake increased linearly (p &lt; 0.05) and backfat thickness at the last rib, backfat thickness at the first sacral vertebrae, P2 backfat thickness, fat area, and the percentage of lean meat decreased linearly (p &lt; 0.05) in pigs. The inclusion of DGP in pig diets did not affect the antioxidant potential evaluated by thiobarbituric acid-reactive substances in mini hamburgers or the quality characteristics of fresh meat, except for intramuscular fat (EE). The dietary inclusion of DGP linearly increased (p &lt; 0.05) EE, saturated fatty acids, monounsaturated fatty acids, and Σω-3 and reduced the ω-6:ω-3 ratio in a linear way (p &lt; 0.05) in the loin of pigs. We concluded that it is feasible to include up to 10% of DGP in pig diets without affecting growth performance, but carcass quality may be impaired due to increased adiposity. Furthermore, meat quality can be improved by increasing intramuscular fat and ω-3 fatty acid content, but fat stability is not affected when DGP is included at up to 10% of the diet for 49 days prior to slaughter.

A five domains assessment of sow welfare in a novel free farrowing system.

The Maternity Ring was developed as a free farrowing alternative to crates that preserved space whilst providing the sow with unrestricted movement. This experiment aimed to apply the Five Domains model to assess sow welfare in the Maternity Ring in comparison with the farrowing crate. Eighty-eight sows were housed in a farrowing crate (FC) and 83 in a Maternity Ring (MR), and measures collected focussed on nutrition, environment, health, behaviour, and mental state outcomes. MR sows consumed less feed than FC sows (total feed intake: 93.8 ± 3.06 kg vs. 111.2 ± 3.13 kg; p < 0.001) but had reduced P2 backfat loss during lactation (0.0 ± 0.11 vs. 1.2 ± 0.11, p < 0.001). Fewer frustrated and pain-related behaviours during farrowing were observed in MR sows (bar biting: FC 3.3 ± 2.12 vs. MR 0.5 ± 0.29 events, p = 0.038, and back leg forward: FC 227 ± 50.7 vs. MR 127 ± 26.4 events, p = 0.019), and a decreased proportion of MR sows had facial injuries after farrowing (10% CI [5, 20] vs. 67% CI [47, 95], p < 0.001). More FC sows had udder damage at weaning (70% CI [48, 97] vs. 10% CI [6, 24], p < 0.001), and their piglets were medicated more frequently when compared to those in MR (51% CI [40, 61] vs. 30% [21, 41], p = 0.008). MR sows tended to have a higher reaction score to piglet processing (MR 2.0 ± 0.38 vs. FC 1.2 ± 0.27, p = 0.094) and had more contact with piglets once the procedure was complete than FC sows (13.5 ± 2.55 vs. 6.9 ± 1.26 events, respectively, p = 0.016). Whilst there was no difference in anticipation of a feeding event (p > 0.05), MR sows displayed a reduced startle response to an aversive noise stimulus at day 18 (FC 2.8 ± 0.35, MR 0.7 ± 0.16, p < 0.001). Using the Five Domains framework, sows housed in the MR during farrowing and lactation have improved welfare than those in FC and can be thought of as being in a positive affective state.

281 Effects of dietary Aspergillus oryzae postbiotic during gestation and lactation on sow and progeny performance

Abstract This study aimed to evaluate effects of Aspergillus oryzae postbiotic (AOP) supplementation in gestation and lactation diets on sow performance, litter performance, and offspring performance through the nursery period. Sows [n = 118; Landrace × Yorkshire; body weight (BW) = 238 ± 2.2 kg; parit y= 3.8 ± 0.32] were blocked by parity and assigned randomly to one of two treatments. Treatments were a control diet and a control diet supplemented with AOP (Biozyme Inc.) at 1.5 g/sow/d in gestation from 5 days before breeding until farrowing, and adjusted to 1.55 g•sow-1•d-1 during lactation. Sow BW and P2 backfat thickness were measured on d 0, 30, and 109 of gestation and 24 h postpartum and at weaning on d 20 ± 2. Litters were standardized to 13 piglets within 24 h of farrowing. Piglets were weighed individually at birth, after 24 h, and at weaning. At weaning, 369 pigs were allotted to pens within maternal dietary treatment (48 pens, with 7 or 8 pigs/pen) for a 42-d nursery trial. All pigs received a common nursery diet in 3 dietary phases. Sows fed AOP had a lighter (P &amp;lt; 0.01) BW than those in the control group on d 109 of gestation (234.1 vs 244.1 kg) and post-farrowing (227.4 vs 236.7 kg), respectively, but not at other time points. Moreover, sows fed AOP showed less (P &amp;lt; 0.01) BW loss from d 109 of gestation to weaning (-0.9 vs -7.8 kg) and from post-farrowing to weaning (4.1 vs -1.9 kg) compared with control sows. Total feed intake and average daily feed intake (Control: 6.0 vs AOP: 6.2 kg/d) during lactation were not impacted (P &amp;gt; 0.10) by dietary treatments. Supplementation of AOP did not influence (P &amp;gt; 0.10) litter size (14.8 vs 16.0), litter birth weight (17.4 vs 18.2 kg), percentage of low birth weight piglets (13 vs 12.5 %) or normal birth weight piglets (87.0 vs 87.5 %), stillbirths (1.2 vs 1.2/litter), or mummies (0.9 vs 0.5/litter) for Control and AOP sows, respectively. Across treatments, no differences (P &amp;gt; 0.10) were observed for litter weight gain (43.2 vs 40.4 kg), average piglet BW at weaning (5.1 vs 4.9 kg), or piglet mortality rate (12.4 vs 13.1 %) for Control and AOP sows, respectively. Piglets weaned from AOP sows tended (P = 0.07) to have an increased average daily feed intake (ADFI) during the first week after weaning compared with pigs weaned from Control sows (0.28 vs 0.26 kg), but AOP did not influence other performance parameters for the entire nursery period. There were no interactions between maternal dietary treatment and nursery phase (P &amp;gt; 0.10), suggesting consistent responses to maternal dietary treatments over time. In summary, feeding sows AOP reduced sow BW loss but had no impact on litter or nursery performance.

Influence of reduced dietary protein level on quality of pork carcasses in Windsnyer pigs

To promote the sustainable production of local pigs, their dietary protein requirements need to be determined. Meat production from these pigs when fed on appropriate diets, coupled with their adaptability to climatic extremes and disease and parasite challenges, could be of huge benefit to the pork industry. The objective of the study was to determine the carcass traits, primary pork cuts, and internal organ weights of pigs fed decreasing dietary protein levels. Thirty, slow-growing, Windsnyer male pigs were randomly allocated to six dietary treatments in a complete randomized design. There were five replications for each of the six treatments. Dietary crude protein levels in the six experimental diets were 193, 174, 154, 135, 116, and 97 g/kg, respectively. The diets were formulated to contain similar net energy levels of ~9.5 MJ/kg. Lysine, methionine, threonine, and tryptophan levels were the same for all diets. A two week adaptation was followed by an 8w feeding phase. At slaughter, pigs had an average weight of ~39.13±0.85 kg. Pigs were humanely slaughtered at the end of feeding period to determine carcass characteristics, primary pork cuts, and internal organ size. A negative linear relationship was observed between protein levels and cooler shrink. There was a positive linear relationship between protein level and dressing percentage, cooler shrink, and shoulder fat. There was a quadratic relationship between dietary protein level and shoulder fat, ham diameter, P2(3) backfat depth, and kidney weight. The thickness of dorsal fat at the last rib, the thickness of back fat, and the width of back fat at P2(2) increased linearly as protein level decreased. The reduction in dietary protein level had an influence on carcass traits, primal pork cuts, and internal organs in slow-growing Windsnyer pigs. A reduction in dietary protein level below 116 g/kg compromised ham diameter, P2(3) width of back fat thickness, shoulder fat, and kidney weight.

Maternal supplementation with phytogenic additives influenced the faecal microbiota and reproductive potential in sows

Sows undergo physiological stress during gestation and lactation, potentially leading to enteric dysbiosis and reduced reproductive potential. Phytogenic additives (PFs) may improve performance via their antioxidant, anti-inflammatory and antimicrobial properties. This study determined whether the provision of a gestation/lactation diet containing PAs would alter the gastrointestinal microbiota of sows and their piglets, and improve performance. Sows received a commercial diet throughout gestation and lactation (CTR; n = 64), a commercial diet throughout gestation and a diet containing PAs in lactation (CTR-PA; n = 63) or a commercial diet containing PAs in gestation and lactation (PA; n = 90). Sows were weighed and backfat recorded after mating and at entry and exit from the farrowing house and piglets were weighed on days 1 and 21 of life. Faecal samples collected from sows at farrowing house entry and piglets at 21 and 35 d were subjected to 16 S rRNA gene amplicon analysis. The addition of PAs to sow diets resulted in more piglets born (P = 0.03), however, it did not improve the number of liveborn piglets (P = 0.14). There were no differences in sow weight, P2 backfat depth or lactation feed intake observed. PAs had no effect on piglet weight or survival to weaning but did alter the faecal microbiota of sows, and this change was observed in piglets at 21 and 35 d. PA supplementation to sows has the potential to increase litter size, while also potentially influencing gastrointestinal tract health of the sow and piglets reared.

Influence of Backfat Thickness and the Interval from Altrenogest Withdrawal to Estrus on Reproductive Performance of Gilts.

Simple SummaryAltrenogest, also known as allyl trenbolone, is a steroidal progestin that is widely used in veterinary medicine to synchronize estrus in gilts. To achieve the target number of services per week, enough weaned sows and gilts are needed each week for breeding. A problem with progestogen-synchronized replacement gilts is the variation of the interval between last feeding of altrenogest and onset of estrus. In the present study, we found that gilt backfat thickness had a strong positive correlation with the interval between last feeding of altrenogest and onset of estrus. This result may come from a larger reservoir of altrenogest in adipose tissue in fatter gilts.Estrus synchronization of gilts can be achieved by feeding the orally active progestogen altrenogest (AT) to cycling gilts at 20 mg/day for 14 to 18 days with gilts usually returning to estrus 4 to 8 days after the last feeding. In practice, gilts failing to exhibit estrus by 6 days after AT withdrawal may compromise weekly breeding targets. The cause of prolonged intervals to estrus are unknown but may involve prolonged suppression due to the release of progesterone (P4), and by extension AT, from adipose tissues. The present study examined relationships between gilt P2 backfat depth (<13.5 mm, 14–16.5 mm, >17 mm groups), the AT withdrawal to estrus interval, and subsequent reproductive performance in gilts. We noted longer intervals to estrus in gilts with greater P2 backfat depths (p < 0.0001), and higher serum P4 concentrations on the last day of AT feeding and at estrus detection (p < 0.05). Total born litter sizes were unaffected by backfat depth, but pigs born alive progressively decreased with increasing backfat depth with the fattest gilts producing the fewest liveborn pigs (p < 0.05). Taken together, these data suggest that adipose tissues may provide a reservoir of steroid, with its release from fatter gilts having potential negative effects on their subsequent reproductive performance.

Body weight and ultrasound measurements over the finishing period in Iberian and F1 Large White × Landrace pigs raised intensively or in free-range conditions

Iberian (IB) pigs are often finished on grass and acorns, and they are known for their ability to deposit high amounts of fat. Live weight, body dimensions and backfat depth measured by ultrasounds in various layers and backfat depots, were collected in an experimental group (n = 117) of IB and crossbred Large White × Landrace pigs (F1), finished either intensively or in oak-tree forests in a factorial experiment. Weight and ultrasounds data were collected at the beginning, midpoint and end of the finishing period, which occurred at a mean live weight of approximately 85, 125 and 160 kg, respectively. Changes in live weight and fat depth over the finishing period were assessed and body dimensions and backfat depth measured by ultrasounds were used to predict carcass traits. Genetic groups differed considerably in growth rate (P < 0.01), with higher ADG in IB than in F1 pigs by about 200 and 80 g/d in the first and second stages of finishing, respectively. Finishing system also affected growth rate (P < 0.01), with faster growth in intensively finished pigs, by about 380 g/d in stage 1 and 220 g/d in stage 2 of finishing. The mean ADG was always higher in the first than in the second stage of finishing, particularly in IB pigs and those finished intensively. In all fat depots considered, the internal fat layer was thicker than the external layer. The major differences in backfat thickness were observed between genetic groups while differences between finishing systems were smaller and often not significant (P > 0.05). At the end of the finishing period, total backfat was about twice thicker in IB than in F1 pigs in the dorsal and P2 depots (P < 0.05), and nearly 50% thicker in rump backfat (P < 0.05). The correlations between dorsal and P2 backfat measurements obtained in carcasses at 24 h post mortem and the same measurement obtained by ultrasounds right before slaughter were near 0.85 for total and internal backfat layers (P < 0.05), but dropped to about 0.3 to 0.6 when estimated within genetic group. Stepwise regression equations estimated to predict various carcass and meat traits indicate that morphometric characteristics had a modest contribution for most carcass traits while the depth of the internal layer of P2 backfat was of major importance in many cases. The ability to predict dressing percentage and abdominal fat had modest accuracy, while ham tissue composition and intramuscular fat percentage could be accurately predicted based on in vivo indicators.

Investigating the reproductive performance of gilt progeny entering the breeding herd

Objective: To quantify the performance of gilt progeny in the F1 breeding herd at a large swine farm in New South Wales, Australia (Rivalea Australia Pty Ltd). `Materials and methods: Performance data on all gilts selected for entrance to the commercial breeding herd from January 2014 until December 2015 were included in this study. Comparisons were made between gilt and sow progeny in terms of the proportion of animals to reach first breeding, performance to parity 4, and longevity to parity 3. Results: Gilt progeny were lighter than sow progeny at each live weight measurement (P &lt; .001), and had a higher P2 backfat level at selection than sow progeny (P = .02) at the same live weight. Gilt progeny selected into the breeding herd reached first breeding before 220 days of age less often than sow progeny (P &lt; .001) and were 1 day older at first breeding (P = .003). Sow progeny had a lower farrowing rate from this breeding (P &lt; .001). After the first breeding, there were few differences in performance indices between groups for the first four parities. There were no statistically significant differences between the groups in terms of longevity indices. Implications: Fewer gilt progeny may be selected to enter the breeding herd; however, after farrowing their first litter, selected gilt progeny perform just as well as sow progeny. While it is recommended to continue to include gilt progeny in the replacement-gilt selection process, further research in this field is recommended.

Allzyme SSF supplementation improves the utilization of sweet potato (Ipomoea batatas) vine meal by growing pigs

ABSTRACTThe effects of Allzyme SSF supplementation of sweet potato vine meal (SPVM) on the performance of growing pigs were investigated. A control diet based on fish meal and full-fat soybean as protein sources and diets containing 150 and 300 g/kg of SPVM with and without SSF were fed each to pigs in five replicates pens in a completely randomized design for a period of 84 days. There was no treatment effect (P > .05) on dry matter intake. The highest body weight gain was recorded on the SSF- supplemented SPVM groups (P < .05) and the lowest (P < .05) on the SPVM-based diets without enzyme. Dressing percentage and P2 back fat thickness were not affected by dietary treatment (P > .05), but per cent ham was markedly reduced on the control compared with the enzyme-supplemented SPVM diets (P < .05). The relative weight of digesta in the stomach and small intestine was not affected by the diet (P > .05). Allzyme supplementation significantly reduced digesta weight in the large intestine (P < .05) even at 30% dietary SPVM. It was concluded that supplementation of the diet with Allzyme SSF will improve the utilization of up to 30% SPVM by grower pigs, reduce cost of pork production and add value to this by-product.

Condition of sows during reproductive activity depending on lipid metabolism gene (DGAT1) polymorphism

Abstract Mutations at gene loci associated with body lipid metabolism may affect not only carcass and meat quality traits in young animals but also the production results of mother sows. The objective of the study was to determine the effect of mutations in the DGAT1 gene, found in Polish populations of maternal breeds, on condition of gilts and later on condition and reproductive performance of sows during three reproductive cycles. The study involved 118 gilts of maternal breeds (Polish Large White (PLW ) and Polish Landrace (PL)). Gilts and subsequently sows were monitored for body weight (BW) and P2 backfat thickness over three reproductive cycles and their litters were analysed for the number and body weight of the piglets. A total of 354 litters of pigs were evaluated. In the analysed pig populations, a single mutation (A/G) in the DGAT1 gene (rs45434075) had a significant effect on deposition of subcutaneous fat only in the PLW gilts (P2G, AA,AG&lt;GG P≤0.05 and P2F r=214 P≤0.01). As regards the G/A 3’UTR polymorphism of the DGAT1 gene (rs342152658), this mutation is negatively correlated only in the PL sows with fatness during their reproductive life and with BW of the piglets reared to 21 d of age. Sows of the DGAT1GG 3’UTR genotype had significantly lower P2F backfat thickness (P≤0.05) and, during a 21-d lactation, reared lighter piglets (P≤0.01) compared to sows of the same breed with the DGAT1AG 3’UTR genotype. The analysed traits were also affected by the interaction between mutations in the DGAT1 gene of the sows of maternal breeds (DGAT1/DGAT1 3’UTR). Sows of the DGAT1GG/GG genotype were characterised by the highest backfat thickness on selection day, and during three reproductive cycles they reared significantly more piglets compared to sows of the DGAT1AA/AG genotype. Heterozygous sows (AG/AG) reared significantly heavier piglets than sows of the AA/GG and AG/GG genotypes (P≤0.05).

Effect of feed wastage on piggery effluent characteristics

Across the Australian pork industry, a 5% change in feed wastage is 82 000 tonnes feed/year, with a current value of approximately $38m. While its importance is widely recognised, there are currently no practical robust methods to quantify feed wastage. Feed wastage influences feed efficiency, shed (manure), effluent management practices and effluent characteristics. Accordingly, the present study hypothesised that feed wastage could be estimated from effluent characteristics. To relate feed wastage to effluent characteristics, the study used an innovative modelling and experimental approach to simulate different rates of feed wastage and assess its effects on piggery effluent. Quantities of pig feed (wheat and barley based grower diet), faeces, urine, flush water (clean bore water) and shed effluent (collected over 24 h in an agitated sump) were sampled from a commercial batch grower shed, housing 535 pigs (average 45 kg live weight at 13 weeks of age). Pre-determined proportions of these samples were mixed to simulate shed effluent having four different rates of feed wastage (Treatments A–D). Treatment A was composed of faeces, urine and flush water only, to simulate zero feed wastage. Treatment B was raw effluent discharged from the shed. Treatments C and D were composed of raw shed effluent with added feed, to simulate higher rates of feed wastage. The resulting samples were analysed to evaluate the total solids (TS), volatile solids (VS) and biochemical methane potential (BMP). Analyses of variance (ANOVA) followed by protected least significant difference (l.s.d.) testing were performed on the analysis results, at the 5% level, using Genstat 16.1 (VSN International, Hemel Hempstead, UK). The AUSPIG growth and production simulation model (Davies et al. 1998) was used to simulate the age, live weight, P2 back-fat and feed intake of the pigs in the trial shed over their entire growth cycle (wean-to-finish). The genotype settings and feed intake factors in the model were adjusted so that measured and predicted performance parameters (growth rate, P2 backfat and feed intake) were similar for the batch of pigs. For each of the four treatments, the extent of feed wastage was then estimated using the AUSPIG model (as reference for comparison) and separately by total solids mass balance.

Replacing starch with fat in the diet is more effective at enhancing overall performance in finisher than grower pigs

SUMMARYThe addition of supplementary fat to pig diets above current dietary recommendations has generally been viewed in a negative manner because it is considered that the surplus energy will be deposited into adipose tissue, and may therefore be detrimental to carcass value. The current study sought to investigate the effects of adding supplementary fat, in place of starch, to increase the energy density of male and female pig diets on growth performance and carcass quality. A total of 288 Large White × Landrace male and female pigs (boars and gilts) were randomly allocated to pens of 12 pigs each. The effects of (i) sex (gilts v. boars), (ii) added dietary fat level (as tallow; 0 v. 40 and 80 g/kg) and (iii) within added dietary fat level (40 v. 80 g fat/kg), were tested for a 5-week period (Period 1) (n = 4). These diets were formulated to contain 13·5, 14·3 and 15·2 MJ digestible energy/kg for 0, 40 and 80 g added fat/kg, respectively; the calculated standardized ileal digestible lysine content was kept constant at 8·8 g/kg of diet. Thereafter the experiment was designed to test for the same effects over a second 5-week period (Period 2), during which pigs from the initial three treatments were offered the diets with 0 and 40 g added fat/kg. Treatment effects were also assessed over the whole 10 weeks of the study. There was a positive linear effect of dietary fat supplementation in Period 1 on average daily weight gain, whereas dietary fat level in Period 1 had no effect on performance in Period 2, overall, or on carcass weight and P2 backfat thickness (i.e. thickness of fat at 65 mm down the left side from the midline, at the level of the head of the last rib) at 10 weeks. In contrast, supplementation of the diet with 40 g fat/kg during Period 2, regardless of the diet offered in Period 1, increased ADG in the second period and over the entire experiment. There were minimal effects of supplementary fat on feed intake in the entire experiment; however feed conversion ratio (FCR) was influenced by sex over the entire study and tended to be reduced by dietary fat supplementation in Period 2. The diet with 40 g added fat/kg fed in Period 2 increased carcass weight by an average of 2·8 kg and P2 backfat thickness by 1·2 mm. Collectively, the data from the current study suggest that dietary fat supplementation is more effective in finisher pigs than in grower pigs in terms of growth rate, FCR and carcass weight.

Por�wnanie zmian otluszczenia loch w ciazy wysokiej i przy odsadzeniu miotu oraz okreslenie ich zwiazku z wynikami rozrodu i odchowu prosiat

Sixty crossbred sows were investigated for the effect of the level of fat reserves in high pregnancy and pre-weaning changes in lipid reserves on reproductive performance of sows and rearing of piglets. At 104 days of pregnancy and at weaning, sows were analysed for body weight, P2 and P4 backfat thickness and M. Longissimus dorsi (MLD) thickness at P4M (Piglog 105). Sows were grouped according to mean backfat thickness (P2 + P4)/2 at 104 days of pregnancy into primiparous (P2 + P4)/2>18 mm (group I), primiparous (P2 + P4)/2≤18 mm (group II), multiparous (P2 + P4)/2>20 mm (group I) and multiparous (P2 + P4)/2≤20 mm (group II). The body weight of sows from group I was higher than sows from group II at 104 days of pregnancy (P ≤ 0.05) and at weaning (P ≤ 0.01). As assumed in the experiment, fatness in high pregnant sows (points P2 and P4) was significantly higher in group I than in group II (P ≤ 0.01), and the differences between the groups persisted when piglets were weaned (P ≤ 0.01). At weaning, sows from group II had a significantly greater P4M thickness compared to sows from group I. The differences in backfat thickness in late-pregnant sows in groups I and II and in the loss of fat reserves during a 21-day lactation had no effect on reproduction results and rearing of piglets. Sows lost body weight to a small extent and fat reserves to a moderate degree; the changes were greater in primiparous than multiparous sows, regardless of the group (I or II).

Dietary chromium picolinate of varying particle size improves carcass characteristics and insulin sensitivity in finishing pigs fed low- and high-fat diets

The aim of the present study was to evaluate the effect of the different-sized particles of chromium (Cr) picolinate (CrPic) and dietary fat on growth performance, carcass traits and insulin sensitivity of finishing pigs. Ninety-six Large White × Landrace gilts were stratified on bodyweight, housed in pens of three pigs and then, on a pen basis, randomly allocated to eight treatment groups in a 2 × 4 factorial design for 6 weeks. The respective factors were dietary fat (2.2% or 5.7%) and dietary CrPic (0 mg/kg, 400 mg/kgnormal-size CrPic, 400 mg/kg 1-μm CrPic (μCrPic), or 400 mg/kg 100-nm CrPic (nCrPic)). Over the first 21 days, average daily gain (ADG) was increased by dietary CrPic (0.94 vs 1.01 kg/day, P = 0.021), although there was no difference (P = 0.17) between the CrPic particle sizes. High dietary fat also increased ADG over this period (0.96 vs 1.03 kg/day, P = 0.013). However, the responses to both dietary CrPic and fat diminished over time and so there was no effect of CrPic (P = 0.35) or fat (P = 0.93) on ADG over the full 42 days. Dietary CrPic increased carcass weight and muscle depth and decreased P2 backfat. Furthermore, dietary Cr decreased plasma insulin (7.66 vs 5.09 mU/L, P = 0.018) and the homeostatic model assessment (1.25 vs 0.82, P = 0.009), indicating an improvement in insulin sensitivity. In conclusion, dietary Cr can increase ADG and improve carcass traits and insulin sensitivity in lean pigs. There were few differences among particle sizes, possibly because the response to dietary CrPic may already be maximised at 400 mg/kg.

Growth performance of heavy pigs fed restrictively diets with decreasing crude protein and indispensable amino acids content

This study aimed to investigate the effect of decreasing dietary crude protein (CP) and indispensable amino acid (AA) content, relative to conventional diets, on growth performance of heavy pigs for dry cured ham production. Four dietary treatments (conventional: CONV, medium-high protein, medium-low protein, and low protein: LP) were formulated by replacing soybean meal with wheat grain to contain 146 to 117 and 133 to 108g CP/kg in early (90 to 130kg BW) and late finishing (130 to 165kg BW) periods, respectively. Within period, diets contained the same amounts of indispensable AA per unit of CP, and the standardized ileal digestible (SID) Lys content was 42.2 and 35.5g/kg of CP in early and late finishing periods, respectively. A total of 240 crossbred pigs, grouped in 3 batches of 80 pigs each, were assigned to one of 4 dietary treatments according to BW and sex (10 pigs per pen, gilts and barrows, and 2 pens per treatment in each batch). Pigs were fed restrictively using a single-space electronic feeder, and feed allowance increased from 2.4 at the start (92±10kg BW) to 3.2kg/d at the end of the trial (167±10kg BW), irrespective of sex. Initial and final BW and backfat depth (P2) measures were used to estimate body composition, and lipid and protein retention (Lr and Pr, respectively). These estimates, along with feed intake data, were used to study the partitioning of ME and SID Lys among body functions. Nitrogen excretion (NEx) was estimated as actual N intake – N retention, and N retention was computed as Pr/6.25. Final BW, average daily gain and final P2 backfat averaged 167kg, 0.665kg/d, and 18mm, respectively. Diet had no effect on these traits, as well as on gain to feed ratio (0.253), Lr (265g/d), Pr (95g/d), and the ME available for maintenance (0.845MJ/kg BW0.60). From CONV to LP the SID Lys intake decreased from 137 to 122g/kg Pr, and NEx decreased by 22%. In this production system, a reduction of dietary CP and indispensable AA content is advisable, as no negative impact on growth performance was observed compared to CONV. A reduced inclusion of soybean meal with a minimal supplementation of AA reduces feed costs and NEx. This would increase the number of pigs raised per unit of land where a maximum N load/ha is constrained by law.

Maternal backfat depth in gestating sows has a greater influence on offspring growth and carcass lean yield than maternal feed allocation during gestation

A commercial pig spends nearly half of its life in utero and its nutrition during this time can influence birth weight and postnatal growth. We hypothesised that postnatal growth is increased in pigs raised by sows with a high backfat depth and high level of energy intake during gestation compared with sows with a low backfat depth and low level of energy intake during gestation. This was tested in a 2×3 factorial design experiment with 2 factors for gilt backfat depth (Thin and Fat) and 3 factors for gestation feed allowance (Restricted, Control and High). Between d 25 and d 90 of gestation, Thin gilts (n=68; 12±0.6 mm P2 backfat) and Fat gilts (n=72; 19±0.6 mm P2 backfat) were randomly allocated, as individuals, to a gestation diet (6.19 g/kg lysine, 13.0 MJ DE/kg) at the following feed allowances: 1.8 kg/day (Restricted); 2.5 kg/day (Control) and 3.5 kg/day (High). For the remainder of gestation and during lactation all gilts were treated similarly. At weaning (day 28), 155 piglets were sacrificed and 272 were individually housed and followed through to slaughter (day 158). At day 80 of gestation, fasted Thin Restricted gilts had lower serum IGF-1 concentrations than Thin High or Thin Control fed gilts (P<0.001). Pigs born from Fat gilts had greater backfat depths (P<0.05), a lower lean meat yield (P<0.05) and were heavier (P<0.05) at slaughter than pigs born from Thin gilts. Gilt gestation feed allowance had only transitory effects on average daily gain and feed conversion efficiency and had no effect on pig weight at slaughter (P>0.05) or lean meat yield (P>0.05). In conclusion, gilts with a backfat depth of ~19 mm at insemination produced pigs that were heavier and fatter at ~158 days of age than those born from gilts with ~12 mm backfat depth at insemination. Maternal body condition during gestation had a more predominant influence on growth parameters of the offspring, such as weight at slaughter and backfat depth, than did feed level during gestation.

Uterine spaciousness during embryo and fetal development in multiparous sows improves birth weight and postnatal growth performance

The offspring of unilaterally cauterized (CAUT) and non-cauterized control (CTRL) sows were used to study the effects of increased uterine space on postnatal average daily gain (ADG), backfat and loin depth, mortality, and adrenocorticotrophic hormone (ACTH) induced cortisol response. At gestation day (D) 35, the total number of embryos was significantly decreased in CAUT sows (CAUT=9.1±3.0, CTRL=15.3±4.3; P=0.001). At birth, piglet weight (WTD0), gender, and morphometrics were recorded. Offspring were weighed at D21 of age, weaning, week (W) 7, 12, 16, and 19 of age. Average daily gain (ADG) was calculated during the lactation (ADGLACT; 0–21days), up to weaning (ADGWEAN, 1–3W), nursery (ADGNUR, 3–7W), finisher (ADGFIN, 7–19W), and birth to market (ADGLIFETIME, 0–19W) periods. P2 backfat (BF) and loin eye (LOIN) depth were measured ultrasonically at 70 and 110kg live weight. Saliva samples were collected from offspring following 5IU/kg ACTH challenge at W12 and W20 of age. Offspring from CAUT sows were heavier than CTRL at birth and D21 (P<0.05), and trended higher at W7 (P=0.06). ADGLACT and ADGWEAN were higher in CAUT pigs (P<0.05). Pigs with higher ADGLACT had higher ADGLIFETIME (P<0.001) after controlling for WTD0. WTD0 however, was the most consistent factor affecting ADG in all growth periods assessed. We conclude that the postnatal growth benefits of additional uterine space associated with a reduction in intrauterine crowding are primarily mediated through increased birth weight. Moreover, improving lactational growth rate can help offset the poor lifetime growth rates of low birth weight piglets.

Current recommended levels of dietary lysine in finisher pig diets are sufficient to maximise the response to ractopamine over 28 days but are insufficient in the first 7 days

Dietary ractopamine increases lean tissue deposition and responses increase as dose is increased provided sufficient dietary lysine is supplied. In Australia, diets supplemented with ractopamine (RAC) are formulated with 0.56 g available lysine per MJ digestible energy. The present study was conducted to investigate the interactions between dietary RAC and lysine on growth and carcass characteristics in ad libitum fed (13.8 MJ/kg) boars and gilts. The study involved 108 individually penned pigs at 17 weeks of age (64.1 ± 0.57 kg) in a 2 by 2 by 3 factorial design, with the respective factors being sex (gilt or boar), dietary lysine (low and high, i.e. 0.56 or 0.65 g available lysine/MJ digestible energy, respectively) and dietary RAC (0, 5 or 20 mg/kg) for 28 days. Over the 28-day study duration, both lysine diets containing dietary RAC were sufficient to elicit a response in average daily gain (ADG) (+5.8%, P = 0.026) and carcass weight (3%, P = 0.045), but not in feed efficiency (FE) (P = 0.555). However, over the period of the first 7 days, there were interactions between the effects of RAC and lysine for FE (P = 0.025) and ADG (P = 0.023), with both traits being responsive only to dietary RAC containing the high lysine, which increased FE (+9.1%, P = 0.002) and ADG (+7.2%, P = 0.068). Dietary RAC improved FE in the latter stages of the study, namely Days 15–21 (+5.7%, P = 0.031) and Days 22–28 (+4.9%, P = 0.040). The high RAC diet reduced carcass P2 backfat (–16.5%, P &lt; 0.001) and fat tissue deposition (–6.2%, P = 0.074) and high lysine tended to reduce fat tissue deposition (–13.3%, P = 0.072). A sex by lysine interaction (P = 0.043) was observed for lean tissue deposition at 28 days, such that only the high-lysine diet increased lean deposition in boars (+11%, P &lt; 0.05) but not in gilts. Dietary RAC tended to increase lean deposition (+14.0%, P = 0.067) in the first 14 days; however, only the high RAC diet increased lean deposition (+9.6%, P &lt; 0.05) over 28 days. In conclusion, the current recommended supplementation levels of lysine for commercial gilts and boars fed RAC may limit the response to dietary RAC if the feeding regime is for short durations and boars will not maximise their lean tissue deposition rates.