Feed not food : alternative feedstuffs for growing-finishing pigs : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University, Manawatu, New Zealand
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Date
2023
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Massey University
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Abstract
Conventional diets used in the swine production sector, which rely heavily on soybean meal (SBM) and cereal grains, do not align with sustainable development goals. Hence, exploring alternative feedstuffs that are inexpensive, environmentally friendly, and do not compete with human food sources is essential to meeting future expectations around sustainability. As pigs are omnivores, they can efficiently convert many types of feed into a nutritious protein source for human consumption. Therefore, research and development in alternative feedstuffs for pigs are ongoing, and farmers are encouraged to adopt these options to enhance the sustainability of their operations. However, incorporating alternative feedstuffs in the diets of grower-finisher pigs requires proper risk management as they can contain high levels of insoluble fibre and other anti-nutritional factors that may affect pig growth performance, pork quality, and welfare.
This thesis aimed to investigate alternative ingredients for inclusion in growing-finishing pig diets. The first experiment (Chapter 3) examined the effect of replacing barley, SBM and soybean oil with dried distiller’s grains with solubles, canola meal, wheat middlings and tallow on pig growth performance and meat quality. There were no negative effects of the alternative diet on overall pig growth or carcass performance, however, skatole levels of backfat were significantly lower in pigs fed the alternative diet.
The second experiment (Chapter 4) investigated the effect of lucerne as an ingredient in grower-finisher diets and as manipulable enrichment material on pig growth performance and behaviour. Feeding the lucerne diet reduced average daily feed intake, live weight gain, feed intake per feeder visit, and feeding rate, but increased feed efficiency. Despite these effects, overall performance was not significantly different between treatments when considering feed conversion ratio, final slaughter weight, dressing out percentage and backfat thickness.
The third experiment (Chapter 5) investigated the effect of replacing SBM with Poultry by-product meal (PBM) in growing-finishing pig diets on growth performance, carcass yield and meat quality. Four experimental diets were formulated, in which SBM was replaced with PBM at the increasing level of 0%, 33%, 77% and 100%. The diets were then fed to growing-finishing pigs. The results clearly demonstrate that PBM can be used as the primary protein source in pig diets without compromising the performance of growing pigs, as long as the diets are properly formulated to meet their nutritional requirements.
A meta-analysis (Chapter 6) was conducted to assess the impact of substituting SBM with alternative oilseed meal, including canola meal, camelina meal, cottonseed meal, sunflower meal and rapeseed meal, on the performance of growing-finishing pigs. The findings indicate that this replacement adversely affected pig's daily weight gain while maintaining daily feed intake, resulting in an increased feed conversion ratio for both growers and finishers. Furthermore, the use of alternative oilseed meals led to reducing carcass and loin yield, although there was no significant impact on meat quality. However, the heterogeneities of the analysis for most parameters were substantial, possibly due to the variation in the nutritive value of the alternative oilseed meal.
Overall, the results showed that substituting conventional feed ingredients with alternative feedstuffs had no or minor impacts on pig growth performance and meat quality. Additionally, several benefits of using alternative feedstuffs ingredients in growing pig diets were identified: reducing skatole in pork from entire males and improving feed conversion efficiency. The present research indicates that using alternative feedstuffs can be a viable option for pig feed, with possible benefits for pig production, meat quality and animal welfare.
The field of alternative feedstuffs for pigs has much to explore, with numerous undiscovered options, such as legumes, brassicas, insects, and by-products, which can offer valuable nutrients and support sustainable pork production. These alternative feedstuffs may have multiple benefits, such as improved gut utilization, support for pig health, lower production costs, and reduced environmental impact. Furthermore, using feed additives to enhance the utilization of low-nutritive-value alternative feedstuffs is a viable option. As such, further research should focus on integrating these feedstuffs into pig diets while promoting sustainable development.
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Figure 2.2 (=Mayorga et al., 2019 Fig 2) was removed for copyright reasons. Figure 2.7 is reused under under a Creative Commons Attribution license (http://creativecommons.org/licenses/by/2.0).
Keywords
Swine, Nutrition, Requirements, Feeding and feeds, Growth