Management strategies to extend feed budgets of grow-finish pigs and the effect on performance, behavioral aggression, and gastric ulceration

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Miller, Kayla Ann
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Gabler, Nicholas K
Kerr, Brian J
Ross, Jason W
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Animal Science
Pork production in the United States and around the world has evolved into a highly integrated and efficient production system due to improvements in facility design, health, management, genetics, reproduction, nutrition, transportation, and packing plant processes. This integration and efficiency are credited to timely breeding, marketing, and slaughtering of pigs. However, this also makes the pork industry more vulnerable to disruptions along the supply chain. This has recently been evident during Porcine Epidemic Diarrhea virus (PEDV) outbreaks (2013), COVID-19 (2020), and cyber-attacks (2021). Under these scenarios, pig producers may need to manage growth and feed budgets to accommodate pig wellbeing and performance. In the case of a foreign animal disease (FAD) outbreak in the United States, heavy restrictions on commercial pig and feed delivery truck movement would be put in place. As such, this poses significant challenges to producers on management strategies that may bring potential negative ramifications to pig performance, welfare, and wellbeing. Therefore, the overall objective of this thesis was to investigate strategies to manage feed budgets of grow-finish pigs and to assess the impact of various diet management strategies on performance, carcass quality, and indices of behavioral aggression and wellbeing. To address the overarching thesis objective, two experiments were conducted, and this research is outlined in research Chapters 2 and 3. In the first research chapter (Chapter 2), a study was designed to explore strategies to extend feed budgets of finishing pigs in the scenario of a FAD outbreak in which, under the state policies, would limit truck movements and ability to move feed between the mill and barns. Under such a scenario, feed budgets will need to be extended with reduced capacity to receive new feed orders. We hypothesized strategies implemented to extend feed budgets would negatively impact growth performance, carcass characteristics, and increase indicators of aggressive behavior. Therefore, to test this Chapter 2 hypothesis, three different strategies to extend feed budgets were evaluated, along with each strategy’s effect on pig performance, behavior, and carcass quality. In comparison to a complete ad libitum Control diet, the following strategies were fed for a 14-day intervention period: 1) feeding group penned pigs based on 1.45x and 2x maintenance metabolizable energy requirement for optimal growth, 2) tightening feeders to the lowest setting to extend feed, and 3) feeding locally sourced, unprocessed whole corn kernels. This period was then followed by a 7-day recovery period, where all pens had ad libitum access to a complete corn-soybean meal diet. Results from this chapter validate strategies to extend feed budgets. As expected, these feed restriction strategies attenuated growth performance. Group-housed finishing pigs can be fed on 1.45x or 2x maintenance basis or by tightening the feeder settings to limit pan coverage to extend feed budgets. Further, sourcing locally stored whole unprocessed corn kernels within the restriction zone could be a viable strategy to feed pigs and maintain some level of performance and good welfare if feed truck movements are restricted. In consideration of pig welfare and wellbeing, indicators of aggression worsened as competition for feed increased, while other markers of pig wellbeing were only marginally negatively impacted. Overall, the data presented in Chapter 2 indicated that of the three strategies tested, feeding to a restricted level of maintenance, or providing alternative sources of feed could be valuable in the events of disruptions to the supply chain where feed budgets may need to be extended under scenarios such as a FAD outbreak. In agreement with our hypothesis, all strategies extended pen feed budgets and slowed pig growth. However, producers will need to considered strategies to mitigate the increased aggressive behavior and monitor pig welfare. Results from this chapter confirmed strategies to extend feed budgets; however, pig wellbeing and welfare must be considered in adopting strategies recommended. While feeding group penned pigs based on 1.45x and 2x maintenance energy requirements is a potential strategy to extend feed budgets, off-feed events, disease hypophagia and erratic feeding patterns may increase the risk of gastric ulcers. Therefore, Chapter 3 was designed to investigate the impact of limit feeding and corn particle size on gastric ulcer incidence rates and grower pig growth performance. It was hypothesized that feeding a finer particle size ground corn-based diet at a reduced daily allotment would increase severity and incidences of gastric ulcers and reduce ADG, ADFI, and G:F. Two dietary treatments were fed in pelleted form and contained either 350 or 750 µm ground corn, and were formulated to be isocaloric to adjust for energy differences in particle size and contained the same SID Lys:ME. All pigs had ad libitum access for the first 4 weeks, and thereafter fed daily for 14 days on a disease hypophagia feed intake pattern. Over this 14-day period, this equated to approximately 3X, 2X, or 1X feeding based on metabolizable energy requirement for maintenance (MEm), where 3X is approximately ad libitum feed intake. Results from Chapter 3 suggest and validate gastric ulcers are a concern to growing pigs when fed pelleted diets and below ad libitum. Further, this work highlighted the association between pelleted diets, reduced voluntary intake events, and gastric ulcers. Data from this research chapter suggest gastric ulcers are an issue in pigs, regardless of feeding level and particle size fed. These data also suggest that gastric dysfunction extends into the glandular body of the stomach lining and not just the pars esophageal region. Data from Chapter 3 are in partial agreement with our hypothesis in that feeding at a limited feeding level attenuates growth performance, while marginally increases incidence and severity of gastric ulcers in growing gilts. Altogether, the work presented in this thesis demonstrates that strategies to limit feed intake and growth with the intent to stretch feed budgets are achievable with caution to adverse social interactions and impacts to growth performance. Further, if producers limit feed intake to their herds, and especially are feeding a pelleted diet, this may exacerbate the incidences and severity of gastric ulcers in pigs. Producers can apply data from this thesis to their systems in the event of supply chain disruptions where abnormal production practices are needed, and understand potential negative consequences to performance, carcass characteristics, and welfare considerations that are associated with implementing strategies. Hopefully our industry does not need to utilize the data presented in this thesis in the case of a FAD outbreak, however this thesis provides preemptive data should scenarios arise.
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