Functional dietary diversity as opposed to monotony: effect on animal production, welfare, and environmental impact : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University

Abstract

The hypothesis of my research was that providing functional diversity as opposed to dietary monotony will: alter fermentation patterns, increase animal production, and reduce negative environmental impacts, enhance animal welfare, and alter neophobia and partial preference through in utero and early life exposure. Thereby the objective was to determine the effects of altering the functionality of diverse diets (through context, species abundance, species distribution, and temporal availability) on dry matter intake, production, welfare, the environmental impacts, and partial preference compared with animals grazing a monotonous diet. This research was conducted over several experiments. Chapter 3 implemented an in vitro rumen fermentation methodology to determine if diverse versus monotonous diets altered fermentation patterns and allowed for assumptions on production and environmental impacts. The results showed that increasing the portion of chicory, plantain, or a diverse combination (chicory, plantain, and alfalfa) to ryegrass increased 24 hr gas production and branched-chain volatile fatty acid production, while reducing ruminal ammonia concentration. Chapter 4 applied an equal parts dry matter (DM) diverse combination diet to ram lambs and compared their intake, performance, welfare, and urinary nitrogen excretion to those offered a repetitive ryegrass diet. Lambs grazing the diverse diet had a 48% greater dry matter intake (DMI), 92% greater average daily gain (ADG), 25% lower day-to-day coefficient of variation (CV) of intake, and had a 30% lower urinary N concentration. Ram lambs provided a varied diet with set ratios of each species had a 20 and 10% greater DMI and a 29 and 23% reduced DMI CV compared to a diverse diet of the same ratios and a ryegrass diet that were monotonous in presentation in the experiment in chapter 5. The experiment in Chapter 6 explored the diverse and varied diet treatments without the restrictions of set ratios of species and compared them to a monotony of alfalfa. At the same level of intake the varied diet lambs gained 67 and 28% greater than the diverse and alfalfa diet. This greater ADG of the varied lambs occurred with the same intake and diet primary chemistry as the diverse diet, indicating that performance was affected by more than primary chemistry. Lambs consuming the alfalfa treatment conducted 150% more v bouts of stereotypic behavior than the diverse and varied lambs. Chapter 7 provided ewes in the final third of gestation with diverse or monotonous ryegrass diets. I found that diverse ewes birthed heavier lambs and exhibited lower levels of oxidative and metabolic stress 24 hrs after lambing. In chapter 8 the lambs birthed in chapter 7 remained with their dams on their respective treatment until weaning (early life experience) or were removed 24 hrs after lambing to pinpoint the effect of in utero and early life on partial preference and neophobic behaviors in later life. Lambs with early life exposure had partial preference altered more than those with only in utero exposure. Lambs exposed to ryegrass in utero or in utero and in early life spent more time grazing ryegrass than their diverse counterparts. In general, the diverse lambs had reduced latency to graze the diverse species compared to the ryegrass lambs. Further, all lambs chose to comprise a mixed species diet. This chapter demonstrated how in utero and early life experience can reduce neophobic behavior and that when provided the choice animals prefer to comprise a diverse diet even if a familiar forage species is available.