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.

Gilt progeny (GP) are born and weaned lighter than sow progeny (SP) and have higher rates of mortality. This study aimed to quantify the performance and survival differences between GP and SP throughout the entire production cycle from birth to sale. Furthermore, the study looked at the effects of segregating GP and SP compared with commingling during rearing within common pens. It was hypothesized that GP would be lighter than SP at every age and have lower rates of survival accompanied by higher rates of medication, and that segregating GP and SP would improve the growth and survival of both groups. All progeny born to 109 gilts (parity 1) and 94 sows (parities 2 to 8) were allocated to 4 postweaning treatments at birth: GP separately penned, GP mixed with SP in a common pen (GM), SP separately penned, and SP mixed with GP in a common pen (SM), with littermates split among treatments. The GM and SM pigs were penned together after weaning. Individual live weight of all progeny was recorded at birth (birth weight [BWT]), weaning (28 d; weaning weight [WWT]), 10 wk of age (10-wk weight [10WT]), and sale (22-23 wk; sale weight [SWT]). Individual HCW, backfat depth, loin depth, and dressing percentage were measured at slaughter. All postweaning mortalities and medications were recorded. The GP had a lighter BWT ( = 0.032), WWT ( < 0.001), 10WT ( < 0.001), and SWT ( < 0.001) than SP as well as a lower HCW ( < 0.001) and dressing percentage ( = 0.012). Postweaning performance differences were mostly attributable to the lighter WWT of GP compared with that of SP when WWT was fitted as a covariate. The GP had a higher mortality in the immediate postweaning period (weaning to 10 wk of age; = 0.028) and from weaning to sale ( = 0.012) than SP, which was also attributable to lower WWT. The GP exhibited a higher incidence of mortality ( = 0.011) due to respiratory tract infection in the grower-finisher period, despite similar medication rates ( = 0.83). Segregation of GP and SP between pens presented no benefit in terms of growth and survival of both groups while requiring added labor and production considerations and, therefore, is not recommended. This study confirms that GP are lighter than SP, on average, at every stage of life from birth to slaughter and that their performance before weaning is an important determinant for whole-of-life performance.

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 < .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 < .001) and were 1 day older at first breeding (P = .003). Sow progeny had a lower farrowing rate from this breeding (P < .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.

Animal Production Science (continuing Australian Journal of Experimental Agriculture) publishes original research into applied agriculture including animal production, animal-plant interactions, pasture and fodder crops, field crops, extension and horticulture

Animal Production Science (continuing Australian Journal of Experimental Agriculture) publishes original research into applied agriculture including animal production, animal-plant interactions, pasture and fodder crops, field crops, extension and horticulture

Animal Production Science (continuing Australian Journal of Experimental Agriculture) publishes original research into applied agriculture including animal production, animal-plant interactions, pasture and fodder crops, field crops, extension and horticulture

Animal Production Science (continuing Australian Journal of Experimental Agriculture) publishes original research into applied agriculture including animal production, animal-plant interactions, pasture and fodder crops, field crops, extension and horticulture

Animal Production Science (continuing Australian Journal of Experimental Agriculture) publishes original research into applied agriculture including animal production, animal-plant interactions, pasture and fodder crops, field crops, extension and horticulture

Animal Production Science (continuing Australian Journal of Experimental Agriculture) publishes original research into applied agriculture including animal production, animal-plant interactions, pasture and fodder crops, field crops, extension and horticulture

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.

Three studies investigated the effect of feeding strategy on production performance and endocrine status of growing pigs. For Experiment 1, 20 entire male pigs (70.0 ± 4.6 kg) were allocated randomly to individual pens in one of four climate-controlled rooms. Pigs were fed for 23 days either ad libitum or entrained to feed bi-phasically for two 90-min periods. For Experiment 2, 20 entire male pigs (41.2 ± 3.5 kg) were housed as per Experiment 1. Pigs were fed for 49 days either ad libitum or fed bi-phasically for two 60-min periods. For Experiment 3, 100 female pigs (66.1 ± 3.5 kg) were randomly allocated to individual pens within a commercial piggery and fed for 42 days either ad libitum or bi-phasically for two 60-min periods. Ear vein catheters were inserted into 10 pigs from each group and hourly blood samples were collected for 24 h in Experiments 1 and 2 and for 11 h in Experiment 3. Plasma insulin, non-esterified fatty acid and glucose concentrations were determined in Experiments 1 and 2, and glucose and insulin concentrations in Experiment 3. Feed intake and performance were recorded in all experiments and carcass composition was assessed by computed tomography for Experiment 2. There were no differences in final liveweight between the two treatment groups for all experiments. Pigs fed for two 90-min periods (Experiment 1) showed no difference in feed intake when compared with feeding ad libitum. Pigs in Experiment 2 fed for two 60-min intervals consumed 2.49 kg/pig.day compared with those fed ad libitum that consumed 2.68 kg/day (P = 0.057). In Experiment 3, pigs fed twice daily consumed 2.82 kg/pig.day compared with 2.91 kg/pig.day in ad libitum-fed pigs (P = 0.051). Bi-phasic fed pigs in Experiment 2 had improved (P < 0.05) feed conversion efficiency compared with pigs fed ad libitum. For all experiments, there was no difference in plasma glucose concentrations between the two treatments. In all three experiments, the circulating insulin concentrations for pigs fed ad libitum remained at a constant level throughout the sampling period. However, plasma insulin concentrations for the bi-phasic fed pigs significantly increased ~1 h after both feeding periods during all three experiments. Insulin secretion of pigs fed for two 90-min periods differed from that of pigs fed for two 60-min periods. Plasma insulin concentration increased five-fold following feeding for 60 min, compared with that in pigs fed for 90 min, which increased two-fold. Bi-phasic-fed pigs from Experiment 2 had reduced (P < 0.05) total carcass fat and significantly increased muscle when compared with pigs fed ad libitum. The data showed that feeding pigs at two succinct periods aligned insulin secretion to the time of feeding. Pigs fed for 60 min, unlike those fed for 90-min intervals, had reduced feed intake in comparison to those fed ad libitum. This may suggest that the duration of the feeding bout is important for this response and this may in turn influence both energy balance and the way energy is partitioned.

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 concept of nutrient synchrony depends on supplying dietary glucose and amino acids (AA) in a synchronised manner to increase nitrogen (N) utilisation efficiency by minimising the energy-dependent conversion of certain AA to glucose or glucose to AA (van den Borne et al., 2007). The hypothesis tested was that the whole body N retention rate would be limited in pigs fed a nutrient asynchronised diet compared to pigs fed a synchronous diet.

Birth weight positively predicts postnatal growth and performance in pigs and can be increased by sustained maternal porcine ST (pST) treatment from d 25 to 100 of pregnancy (term ∼115 d). The objective of this study was to test whether a shorter period of maternal pST treatment in late pregnancy (d 75 to 100) could also increase birth and weaning weights of progeny under commercial conditions. Gilts (parity 0) and sows (parities 2 and 3) were not injected (controls) or injected daily with pST (gilts: 2.5 mg•d(-1), sows: 4.0 mg•d(-1), both ∼13 to 14 μg•kg(-1)•d(-1)) from d 75 to 100 of pregnancy. Litter size and BW were recorded at birth and weaning, and dams were followed through the subsequent mating and pregnancy. Maternal pST injections from d 75 to 100 increased litter average progeny weight at birth (+96 g, P = 0.034) and weaning (+430 g, P = 0.038) in sows, but had no effect on progeny weight in gilts (each P > 0.5). Maternal pST treatment did not affect numbers of live-born piglets and increased numbers of stillborn piglets in sows only (+0.4 pigs/litter, P = 0.034). Maternal pST treatment did not affect subsequent reproduction of dams. Together with our previous data, these results suggest that sustained increases in maternal pST are required to increase fetal and postnatal growth in gilt progeny, but that increasing maternal pST in late pregnancy may only be an effective strategy to increase fetal and possibly postnatal growth in sow progeny.

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 similar to 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.

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

Piglet neonatal survival and postnatal growth and efficiency are positively related to birth weight. In gilts, daily maternal porcine ST (pST) injections from d 25 to 100 (term approximately 115 d), but not d 25 to 50, of pregnancy increase progeny birth weight. Daily maternal pST injections from d 25 to 50 increase fetal weight at d 50 in gilts and sows. We therefore hypothesized that daily pST injections from d 25 to 100, but not d 25 to 50, of pregnancy would increase birth weight similarly in both parities. Landrace x Large White gilts and sows were uninjected (controls) or were injected daily with pST (gilts: 2.5 mg/d; sows: 4.0 mg/d, each approximately 15 microg of pST/kg per day) from d 25 to 50 or 100 of pregnancy. Litter size and BW were recorded at birth, midlactation, and weaning. Dams were followed through the subsequent mating and pregnancy. Maternal pST injections from d 25 to 100, but not d 25 to 50, increased mean piglet birth weight by 11.6% in sows (P 0.1) the weaning-remating interval, conception rate, or subsequent litter size. Greater pST-induced birth weight increases in sows than in gilts may mean that underlying metabolic or placental mechanisms for pST action are constrained by maternal competition for nutrients in rapidly growing gilts.