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Title: Identifying, understanding and harnessing the beneficial impact of nutritional interactions to optimise the performance and carcass quality of low birth weight pigs
Author: Hawe, Samuel
Awarding Body: Queen's University Belfast
Current Institution: Queen's University Belfast
Date of Award: 2020
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This research study was undertaken to determine the key characteristics of low birth weight pigs in a commercial setting as well as to investigate a number of intervention strategies within a research setting to uplift the lifetime growth and carcass performance of low birth weight pigs to levels comparable to average birth weight pigs. Particular emphasis was placed on increased nutrient supply to pigs through enhanced sow lactation feed intake, as well as tailored post-weaning feeding regimes. Due to the lack of recent data reporting the lifetime performance of commercially reared pigs born into large litters (>14 piglets), this research initially aimed to quantify the growth and mortality rate of low and average birth weight pigs throughout their lifetime on commercial farms in Northern Ireland. The extent of pre-weaning mortality due to various causes differed with birth weight (P<0.05), with starvation (49%) and overlying (28%) accounting for the majority of Low BW mortalities. With regard to post-weaning mortality, birth weight had no effect on number of deaths or the age or weight of death (P>0.05). The alimentary tract (27%) and respiratory tract (27%) were the most common body systems associated with deaths following post-mortem examination of all post-weaning mortalities. This study quantified the inferior weight and growth rate of Low BW pigs, along with the major causes of mortality. The lactation and immediate post-weaning periods were identified as having greatest potential for reducing the negative effects of low birth weight on lifetime performance in terms of growth and mortality. Literature and on-farm data indicated that opportunity exists to increase the pre-weaning performance of low birth weight pigs. As such this study aimed to determine the effects of increased sow lactation feed intake on piglet pre- and post-weaning growth, mortality and feeding behaviour. Rearing Low BW pigs on sows offered a High FA during lactation significantly increased total suckling duration, reduced piglet mortality and increased piglet weaning weights. The performance of a cohort of pigs from the work described above was followed through to slaughter to investigate if the superior performance during lactation in pigs from sows offered a High FA was retained. Animals failed to build upon the pre-weaning benefits attained from an increased sow lactation feed intake, with piglet birth weight having a substantially greater impact on performance during the growing and finishing period. The above studies indicated that improvements in weaning weight were achievable, but these benefits were lost during the post-weaning period through to slaughter. The positive relationship between nutrient intake, in particular energy and lysine intake, and growth are well known. Therefore the main aim of this final experiment was to improve the lifetime performance of low birth weight pigs by tailoring energy and protein intakes to match their weight in a pen based, commercial-like setting. Feeding Low BW animals on the basis of weight may have allowed a greater time for digestive development between each diet transition. This increased nutrient intake and, as a result, improved liveweight. As this regime had no detrimental effect on carcass characteristics or body composition it represents a commercial opportunity to increase the slaughter weight of all animals, improving output and profitability at farm level. Summary: This research project has advanced the knowledge and understanding of low birth weight pigs by quantifying their actual performance as well as the performance differential compared to average birth weight pigs on commercial farms. It also indicated the most prevalent time and cause of deaths for both birth weight categories on farms in NI. In contrast to much of the literature, effective intervention strategies employed in a research setting in this work showed that it was possible for low birth weight pigs to achieve the weight of average birth weight pigs. Finally, modelling the change of animal feeding efficiency with increasing liveweight, combined with analysis of animal feeding behaviour and body composition has furthered the understanding of the underlying mechanisms responsible for the elevated performance in low birth weight pigs given enhanced nutrient supply. This work quantified that, on farms in NI, low birth weight animals exhibited a 15% greater level of pre-weaning mortality than average birth weight piglets, with starvation cited as the cause of death in almost 50% of cases. The weight differential between low birth weight animals and average birth weight counterparts increased from 1.2kg at weaning to over 9kg at slaughter, with low birth weight animals requiring an estimated additional 11 days to reach a comparable slaughter weight. Finally, the greatest divergence in growth rate was recorded in the weeks immediately following weaning, highlighting this period as a critical window for intervention. For the first time, this work has found that increasing sow lactation feed allowance halved mortality amongst low birth weight animals compared to those reared on sows offered a low feed allowance or those reared commercially. Furthermore, when reared on sows offered a high feed allowance, low birth weight litters expressed the same suckling behaviour as average birth weight litters during later lactation and had the capacity to effectively utilise the additional milk yield to give an 11% increase in weaning weight. Low birth weight pigs recorded a superior relative growth and relative feed intake between weeks 12 and 22 of age, where FCR deterioration and feeding behaviour did not differ compared to average birth weight pigs. However an overall poorer FCR for low birth weight animals during this period, combined with a poorer feed intake immediately following weaning, meant any pre-weaning benefit was not built upon during the post-weaning period. With regard to post-weaning nutrition, this research project has shown that when dietary transitions were carried out on a weight basis, low birth weight animals were significantly older and heavier at each transition compared to those of an equivalent birth weight fed using a commercial regime. This novel data showed the former method of feeding improved growth to the extent that low birth weight animals fed on a weight basis post-weaning in the research setting were 3% (38.6kg vs 37.3kg) and 8% (71.7kg vs 65.7kg) heavier at week 12 and 17 respectively compared to average birth weight animals reared in the commercial setting. This indicates that it is not only the inferior physiology of compromised pigs which limits growth but also the production system employed. Whilst low birth weight animals were generally associated with a greater percentage of body fat and lower percentage of lean composition compared to average birth weight pigs throughout the growing period, this was not exacerbated by the enhanced feeding regime. Hence this method of intervention represents a commercial opportunity to maximise performance and profitability. This research project outlines a number of opportunities for pig producers to improve productivity and efficiency at farm level. Enhancing nutritional management of the sow during lactation can significantly improve growth and suckling behaviour of low birth weight pigs, whilst reducing pre-weaning mortality. Furthermore, this study highlights that offering a post-weaning feeding regime tailored to animal weight can minimise any post-weaning growth check in low birth weight animals, with no adverse effects on body composition or carcass quality.
Supervisor: Scollan, Nigel Sponsor: Department of Agriculture ; Environment and Rural Affairs
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: low birth weight pig ; lifetime growth ; weaning ; suckling behaviour ; feeding behaviour ; body composition ; large litters ; mortality