NUTRITION AND WELFARE

Nutrition is one of the five welfare domains and an ani­mal’s affective state (welfare) is impacted by food and water (Mellor 2017). Satiation is often considered a requirement of positive welfare; however the sensations of thirst and hunger do not indicate poor welfare.

The nutrient composition and/or presentation of a diet and water may need to be adjusted to allow for shorter or less severe bouts of hunger or thirst. This does not mean feeding ad lib. A properly balanced diet at an energy den­sity similar to the natural diet should result in satiety when nutrient and energy needs are met thus maintain­ing a positive welfare state (Tables 14.1 and 14.2). This can be monitored by assessing and documenting food intake, feeding behaviour, body condition/weight, faecal consist­ency and signs of gastrointestinal comfort/discomfort.

Factors that may lead to overeating can often be understood, anticipated and prevented. Diets that do not provide nutrients within the range of an animal’s natural diet, such as herbivore diets too high in sugar and low in fibre, may disrupt feedback mechanisms for satiation (Spangler et al. 2004; Alcock et al. 2014). Boredom, dis­placement and dominance may be addressed with novel approaches to presenting feeds, offering more feeding stations and/or changing feeding schedules. Body condi­tion and behaviour inform timing of feeding and success of presentation. Behaviours often associated with hunger, such as increased activity, vocalising, pacing, begging and aggression may be anticipatory behaviours in response to feeding cues rather than hunger.

A managed care diet should ensure nutrient value, pal- atability, acquisition and processing time as equal priori­ties. A diet may look, taste and feel natural yet lead to nutrient deficiencies, excess caloric intake or behavioural issues if nutrients are not in balance and the diet offered is not prepared or presented properly. Animals may encoun­ter a variety of flavours, textures and tastes in their natural diet but even specialists (e.g. nectarivores and insectivores)

Fig. 14.3. Examples of gastrointestinal tracts from Australian mammalian carnivores and the cat (Felis catus) as the comparative domestic animal model. Numbat (Myrmecobius fasciatus) image modified from Hume (1999). Short-beaked echidna (Tachyglossus aculeatus), brush-tailed phascogale (Phascogale tapoatafa), domestic cat and little brown bat (Myotis Iucifugus) from Stevens and Hume (1995). *Although these three species exhibit gross characteristics of a carnivore gastrointestinal tract, more in-depth studies on short-beaked echidna may suggest a different model (Perry et al. 2022).

Table 14.1. Nutrient requirements of domestic animals as % or per kg diet on a dry matter basis for diets of listed metabolisable energy (ME)

^a Adult goat (50 kg BW) on a maintenance diet with 40% Undegradable Intake Protein (UIP). UIP is the percent of Crude Protein not degraded by rumen microbes and 40% is an average for a range of diets.

^b Adult sheep (50 kg BW) on a maintenance diet of 40% UIP

^c Adult horse (200-400 kg BW) at minimal activity

^d Mature bull (500 kg BW)

^e Increase magnesium to 0.25% or 0.5% under conditions that predispose to grass tetany (i.e. ruminants grazing on fresh pasture)

'-' Nutrient requirement not listed, indicates dietary need unknown or not demonstrated

¹NRC (2006); ²NRC (1995); ³NRC (2012); ⁴Lebas etal. (2010); ⁵NRC (2007a); ⁶NRC (2007b); ⁷NRC (2001)

may have rewarding experiences generated through form and presentation of diet (Hosey et al. 2013). The ability of an animal to exercise food preference is considered desir­able within the context of a species-appropriate diet. This does not mean allowing an animal to consume only its most favoured food items. Regular diets should not include items that are dramatically outside the nutrient profile of an animal’s natural diet (Wilder et al. 2016). Higher value items tend to be high in nutrients scarce in a species’ natu­ral diet (such as sugar or fat for a grazing herbivore). Once these items are removed, other items will become higher in value. If given the choice, animals will choose to work for a food reward. Adding challenge to acquisition increases processing time and improves the chances of consumption of less preferred items (Hosey et al. 2013). Identifying the higher value items in an animal’s balanced diet and limiting those for use in training, conditioning and medicating is part of a successful nutrition and behav­ioural management program.

The range of food an individual consumes may be influenced by many factors including hierarchical posi­tion, fitness and age. Therefore, in large groups, the presence of varied ingredients at each feeding is not nec­essarily sufficient to confirm that an animal is consum­ing a varied and balanced diet. In these cases, animals may experience a more varied diet if fed less daily variety (but more volume), with variations of items through the week.

• Sufficient nutrient/energy/moisture content of food to meet physiological state of each animal

• Enough for number of animals

• Sufficient watering and feeding stations to avoid competition

• Accessibility (the ability to achieve appropriate drinking or feeding posture)

Table 14.2. Bodyweight (BW) examples and basal and field metabolic rate (BMR and FMR) calculations for selected Australian mammal species

^aDaily basal energy requirements (BMR) are calculated on a metabolic body mass (BW^0.75) basis as BMR (kcal d^-1) = x (kcal kg^-075 d^-1) BW^0.75 (kg⁰'⁷⁵). In eutherian mammals x = 70 (kcal kg^-075 d^-1) and BW^0.75 (kg⁰'⁷⁵) is metabolic bodyweight. In the absence of species-specific exponents for metabolic body mass, kg^0.75 is used for species in this table but the value for x provided is adjusted to account for a lower mean for Australian mammals. BMR modified from Hume (1999).

^bFor those species without a published multiplier of BMR, FMR is assumed to be 150-250% of BMR. Modified from Hume (1999).

Example. Short-beaked echidna weighing 3 kg

Metabolic bodyweight (kg^0.75) = 3^0.75 = 2.28

BMR (kcal d^-1) = 22 ? 2.28 = 50

FMR (kcal d^-1) ranges from 1.5 ? BMR to 2.5 ? BMR = 75 to 125

• Presentation (including form and size of feed items) and feeding schedule is adequate to exhibit natural behaviours, result in appropriate time spent feeding, fasting and reduce anxiety associated with anticipa­tion of feeding

• Absence of water and feed guarding by conspecifics or incursion by pest-species

• No compromise to water or food quality and palatabil- ity (freezing, overheating, stagnant, stale etc.)

• Absence of spilling, contamination or fouling risks

• Absence of species-specific toxicity risks

• Absence of pest species that may consume the target animals’ food (just because the food has gone does not necessarily mean the target animal has consumed it)

3.