C. L. Collins

Improving growth performance of finisher pigs with high fat diets

A total of 1296 pigs (Large White × Landrace) were selected at 16 weeks of age and used to investigate the effects of supplemental dietary fat concentration on finisher growth performance. Pigs were selected at an average weight of 64.0 kg and allocated to a 2 × 6 factorial experiment with the respective factors being sex (entire male and female) and supplemental dietary fat concentration (1, 2, 3, 4, 5 and 6% added tallow). All pigs were offered the respective diets ad libitum from 16 weeks of age through to slaughter at 21 weeks of age. Over the entire 5-week period, feed : gain ratio improved linearly with increasing supplemental fat concentration (P < 0.001), reducing from 2.60 to 2.44 with an increase in dietary fat concentration from 1 to 6%. Improvements in daily gain were more pronounced during the initial 14-day feeding period, increasing linearly (P = 0.002) from 844 g/day (1% fat) to 942 g/day (6% fat). Carcass weight also improved linearly (P = 0.009), increasing from 74.1 kg (1% fat) to 75.8 kg (6% fat). A greater response was observed in the males, with an increase in supplemental fat concentration from 1 to 6% improving daily gain by 7%, reducing the feed: gain ratio from 2.55 to 2.31 and improving profit per pig by AU

Dietary lecithin improves dressing percentage and decreases chewiness in the longissimus muscle in finisher gilts

4.17. The effects of increasing dietary fat concentration were more moderate in females, with potential profit increases of AU

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

1.47. These results suggest that adding up to 6% supplemental fat to finisher diets improves profit under Australian conditions, with the benefits greater in male than female pigs. The economic impact of such a feeding strategy will, however, depend on the pig’s genetic propensity for fat deposition and the pricing system in which the pigs are sold.

Reduced protein intake during the weaner period has variable effects on subsequent growth and carcass composition of pigs

The influence of dietary lecithin at doses of 0, 4, 20 or 80 g/kg fed to finisher gilts for six weeks prior to slaughter on growth performance, carcass quality and pork quality was investigated. M. longissimus lumborum (loin) was removed from 36 pig carcasses at 24h post-mortem for Warner-Bratzler shear force, compression, collagen content and colour analyses. Dietary lecithin increased dressing percentage (P=0.009). Pork chewiness and collagen content were decreased by dietary lecithin (P<0.05, respectively), suggesting that improved chewiness may be due to decreased collagen content. However, dietary lecithin had no effect on shear force, cohesiveness or hardness (P>0.05, respectively). Dietary lecithin reduced loin muscle L* values and increased a* values (P<0.05, respectively) but no changes on b* values (P=0.56). The data showed that dietary lecithin improved dressing percentage and resulted in less chewy and less pale pork.

Evaluation of common vetch (Vicia sativa cv. Morava) for growing 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 < 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 < 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.

Interactions between piglet weaning age and dietary creep feed composition on lifetime growth performance

In total, 960 pigs (480 castrated males and 480 gilts), selected at ~28 days of age, were used to investigate the effect of restricting protein intake for a short period between 4 and 14 weeks of age. Pigs were selected over an 8-week period in groups of 120 pigs (three pens of 20 castrated males and three pens of 20 gilts per week). Pigs were given ad libitum access to commercial diets from weaning to slaughter. Pens of 20 pigs of each sex were allocated to one of six treatments: control (no restriction), restriction from 4 to 7 weeks of age, restriction from 7 to 10 weeks of age, restriction from 10 to 14 weeks of age, restriction from 4 to 10 weeks of age or a restriction from 4 to 14 weeks of age. During the period of restriction, pigs were offered ad libitum commercial diets that had been reduced in dietary lysine to digestible energy ratio by ~15%. Restricting protein intake between 7 and 10, 4 and 10 and 4 and 14 weeks of age reduced daily gain during the period of restriction. Pigs restricted from 7 to 10 weeks of age had reduced average daily feed intake (5.6%) from 7 to 10 weeks, followed by a reduction in average daily feed intake (5.5%) and improved feed efficiency (6.1%) in the subsequent period from 10 to 17 weeks of age. Daily gain for the entire experimental period was similar for all treatment groups, except those restricted from 7 to 10 weeks of age (3.9% lower than the controls), although there was no treatment effect on carcass weight. Interestingly, backfat was reduced by 10% in these animals compared with the controls, which may be economically beneficial in markets where producers are paid on backfat and carcass weight, such as those selling domestically in the Australian market. Economic benefits of reduced feed costs during both the restriction and realimentation periods were also observed when pigs were restricted from 10 to 14 weeks of age. Any economic benefits from short periods of protein restriction will vary depending on the specific market conditions and the local cost of feed protein sources.

Post-weaning and whole-of-life performance of pigs is determined by live weight at weaning and the complexity of the diet fed after weaning ☆

The response to the inclusion of common vetch (Vicia sativa cv. Morava) at levels up to 225 g/kg diet was evaluated in growing pigs between 91 and 161 days of age. A total of 312 male pigs, selected at a liveweight of 37.6 ± 0.24 kg, were group housed in pens of 19–20 pigs, each initially in commercial grower facilities, which were then split within treatment into pens of 9–10 pigs in commercial finisher facilities. Pens were randomly allocated to 1 of 4 diets, 4 pens per diet. Vetch replaced peas in the wheat-based, protein-adequate diets at levels of 0, 75, 150 and 225 g/kg diet, with the digestible energy and lysine levels being similar for each diet. Pigs were offered the experimental grower diets for 4 weeks, followed by the corresponding experimental finisher diet for 6 weeks. Growth performance was not significantly affected by level of vetch up to 225 g/kg during the first 4 weeks of feeding with average growth rate, feed intake and feed conversion efficiency being 871.5 g/day, 1.90 kg/day, and 2.20 kg feed/kg gain, respectively. However, a significant negative linear response was observed for feed intake in pigs between 119 and 161 days of age, which resulted in voluntary feed intake decreasing from 2.62 to 2.44 kg/day when inclusion of Morava vetch increased from 0 to 225 g/kg. A significant curvilinear response was also observed in growth rate and feed conversion ratio during this period. These significant effects during the later growth phase resulted in significant decreases in voluntary feed intake and growth rate from 2.34 to 2.17 kg/day, and from 948 to 873 g/day, respectively, for the entire growth period as Morava vetch was increased from 0 to 225 g/kg diet. Thus, it is suggested that Morava vetch could be fed at rates up to 225 g/kg for pigs between 91 and 119 days of age, but should be reduced to less than 150 g/kg if feeding continues beyond 119 days of age.

Dietary lecithin decreases skeletal muscle COL1A1 and COL3A1 gene expression in finisher gilts

The influences of creep feed composition and piglet weaning age on apparent creep feed disappearance and post-weaning performance were examined. A total of 24 gilts and 72 multiparous sows were selected at farrowing, and their litters allocated to a 2 by 2 factorial arrangement of treatments with the factors being weaning age (22 or 29 days of age) and the composition of the creep feed [simple (diet based predominately on cereals and animal and vegetable protein sources) or complex (diet based predominately on cereals, animal protein sources and 300 g/kg whey powder)]. Creep feed was offered to all litters from 9 days of age to weaning. While creep feed disappearance did not affect pre-weaning growth performance, there was a greater disappearance of the simple creep feed than the complex creep feed from 9 days of age to weaning (776 versus 461 g/litter, respectively, P ≤ 0.004). Apparent creep feed intake from individual piglets in a subset of litters was assessed at three time points (16 and 19 days of age and at weaning), allowing the characterisation of individual pigs as good, moderate, small or non-eaters. There was no difference between treatment groups (χ2 ≤ 6.27, P ≤ 0.71) in the characterisation of apparent creep feed disappearance by individual piglets, however piglets offered the simple creep diet before weaning consumed more feed (P ≤ 0.004) and gained weight faster (P ≤ 0.007) during the first 5 days after weaning than those animals offered the complex creep diet. Feed intake from weaning to 49 days of age also tended to be greater in pigs offered the simple creep diet before weaning (P ≤ 0.053), with this difference reflected in daily gain from weaning to 49 days of age (P ≤ 0.051). Despite these differences, creep feed composition did not influence lifetime growth performance or carcass composition. Pigs weaned at 22 days of age were heavier midway through the weaner period (49 days of age) than pigs weaned at 29 days of age (15.2 versus 14.3 kg, respectively, P ≤ 0.009), and tended to grow faster from birth to slaughter (616 versus 610 g/day, respectively, P ≤ 0.079). These data suggest that the provision of a complex creep diet during lactation may not improve lifetime growth performance above that of a less expensive creep diet. Weaning age may however influence lifetime performance, with weaning at 29 days of age tending to reduce rate of gain from birth to slaughter.

The apparent ileal digestibility of amino acids in common vetch (Vicia sativa cv. Morava)

The production performance and financial outcomes associated with weaner diet complexity for pigs of different weight classes at weaning were examined in this experiment. A total of 720 weaner pigs (360 entire males and 360 females) were selected at weaning (27 ± 3 d) and allocated to pens of 10 based on individual weaning weight (light weaning weight: pigs below 6.5 kg; medium weaning weight: 6.5 to 8 kg; heavy weaning weight: above 8.5 kg). Pens were then allocated in a 3 × 2 × 2 factorial arrangement of treatments with the respective factors being weaning weight (heavy, medium and light; H, M and L, respectively), weaner diet complexity (high complexity/cost, HC; low complexity/cost, LC), and gender (male and female). Common diets were fed to both treatment groups during the final 4 weeks of the weaner period (a period of 39 days). In the first 6 d after weaning, pigs offered the HC diets gained weight faster and used feed more efficiently than those offered the LC diets (P = 0.031). Pigs fed a HC diet after weaning tended to be heavier at the sale live weight of 123 d of age compared with pigs fed the LC diet (P = 0.056). There were no other main effects of the feeding program on growth performance through to slaughter. Weaning weight had a profound influence on lifetime growth performance and weight at 123 d of age, with H pigs at weaning increasing their weight advantage over the M and L pigs (101.3, 97.1, 89.6 kg respectively, P < 0.001). Cost-benefit analyses suggested there was a minimal benefit in terms of cost per unit live weight gain over lifetime when pigs were offered a HC feeding program to L, with a lower feed cost/kg gain. The results from this investigation confirm the impact of weaning weight on lifetime growth performance, and suggest that a HC feeding program should be focused on L weaner pigs (i.e., weaning weight less than 6.5 kg at 27 d of age) in order to maximise financial returns.

Dietary lecithin improves feed efficiency without impacting meat quality in immunocastrated male pigs and gilts fed a summer ration containing added fat

Simple Summary In this study, the effect of dietary lecithin on skeletal muscle gene expression of collagen precursors and enzymes was investigated in gilts. Thirty-six finisher gilts were fed with diets containing either 0, 4, 20 or 80 g/kg soybean lecithin for six weeks. Then, rectus abdominis muscle was sampled and analyzed for eight genes involved in collagen synthesis and degradation (COL1A1, COL3A1, MMP-1, MMP-13, TIMP-1, TIMP-3, lysyl oxidase and α-subunit P4H) using quantitative real-time PCR. The results showed that lecithin down-regulated COL1A1 and COL3A1 as well as tended to down-regulate α-subunit P4H expression. Abstract The purpose of this study was to investigate the effect of dietary lecithin on skeletal muscle gene expression of collagen precursors and enzymes involved in collagen synthesis and degradation. Finisher gilts with an average start weight of 55.9 ± 2.22 kg were fed diets containing either 0, 4, 20 or 80 g/kg soybean lecithin prior to harvest for six weeks and the rectus abdominis muscle gene expression profile was analyzed by quantitative real-time PCR. Lecithin treatment down-regulated Type I (α1) procollagen (COL1A1) and Type III (α1) procollagen (COL3A1) mRNA expression (p < 0.05, respectively), indicating a decrease in the precursors for collagen synthesis. The α-subunit of prolyl 4-hydroxylase (P4H) mRNA expression also tended to be down-regulated (p = 0.056), indicating a decrease in collagen synthesis. Decreased matrix metalloproteinase-1 (MMP-1) mRNA expression may reflect a positive regulatory response to the reduced collagen synthesis in muscle from the pigs fed lecithin (p = 0.035). Lecithin had no effect on tissue inhibitor metalloproteinase-1 (TIMP-1), matrix metalloproteinase-13 (MMP-13) and lysyl oxidase mRNA expression. In conclusion, lecithin down-regulated COL1A1 and COL3A1 as well as tended to down-regulate α-subunit P4H expression. However, determination of muscle collagen content and solubility are required to support the gene functions.