There is little modern data addressing the differential lifetime growth of commercially reared low and average birthweight pigs born into large litters (>14 piglets). As such, the main aim of this study was to quantify the lifetime growth and mortality rate of low and average birthweight pigs on commercial farms in Northern Ireland. It was also aimed to analyse the level, stage and cause of mortality within each birthweight category. A total of 328 low birthweight (LOW BW; <1kg) and 292 average birthweight (AV BW; 1.3kg-1.7kg) pigs were individually identified across four commercial farms and one research farm. Animal growth and mortality was monitored on an individual basis from birth until slaughter age. Av BW pigs were heavier than Low BW pigs throughout the trial (P<0.001), with a weight advantage of 1.16kg at weaning increasing to over 9kg at slaughter age. Av BW pigs recorded a superior ADG to Low BW pigs throughout the trial (P<0.05), with the greatest difference recorded immediately post-weaning between weeks 4 to 8 and weeks 8 to 12 when a 77g/day and 85g/day difference was recorded respectively. Av BW pigs which were cross-fostered were significantly lighter than those remaining with their birth mother at weaning (0.9kg), week 8 (1.7kg) and week 12 (3.1kg) (P<0.05 respectively). Variance of weight was significantly greater for the Av BW pig population than the Low BW pig population at week 4 (P<0.001) and 8 (P<0.05). Pre-weaning mortality of Low BW pigs was over three times greater than that of Av BW pigs (21% vs 6%; P<0.001), with Low BW deaths occurring earlier (9.2 days vs 15.4 days; P<0.001) and at a lighter weight (1.2kg vs 2.4kg; P<0.001) than Av BW pigs. There was a clear association between birthweight and cause of pre-weaning death (P<0.05), with starvation (49%) and overlying (28%) accounting for the majority of Low BW mortalities. Birthweight had no effect on rate, age or weight of post-weaning mortalities (P>0.05). The alimentary tract (27%) and respiratory tract (27%) were the most commonly implicated body systems following post-mortem examination of post-weaning deaths. In conclusion, this study quantified the inferior weight, growth rate and mortality of Low BW pigs, identifying the lactation and immediate post-weaning periods as having greatest potential in reducing this birthweight associated growth differential.
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Identifying, understanding and harnessing the beneficial impact of nutritional interactions to optimise the performance and carcass quality of low birth weight pigsAuthor: Hawe, S., Dec 2020
Supervisor: Magowan, E. (Supervisor) & Scollan, N. (Supervisor)
Student thesis: Doctoral Thesis › Doctor of PhilosophyFile