8.6 Large Animal Nutrition
Overview
Nutrition is very important for managing health, welfare, and production of farm animals, so it is crucial for a veterinary team to be involved in its planning. Feed is the largest cost in animal production. Feed varies with age, breed, production and gain needs, pregnancy status of the animals, and season of the year, such that a client may be responsible for a wide variety of different feeding regimens for the animals under their care. Feeding is also related to a significant number of large animal diseases (Kustritz, 2022a).
The first nutrition a newly born horse, goat, cow, or other animal will have is their mother’s milk. This first milk is called colostrum, and it contains antibodies to help protect them from diseases. It is therefore crucial for young animals to drink this milk soon after birth in high enough quantities.
Ruminants:
Ruminants are grazers that regurgitate and chew food (cud) for further digestion.
As previously discussed in the Digestive System section, cows, sheep, and goats have four stomach chambers: reticulum, rumen, omasum, and abomasum.
- Reticulum: A specialized pouch of the rumen located in the cranial aspect of the abdomen that empties into the rumen
- Rumen: Located on the left side of the abdomen. Serves as a fermentation vat filled primarily with bacteria
- NOT functional at birth
- Functions: Stores feed for regurgitation, soaks feed, physically mixes and break down feed, and ferments feed to produce proteins and vitamins
- Omasum: Absorbs water and breaks down the ingesta into small particles
- Abomasum: The “true stomach” that secretes digestive enzymes; it is a glandular stomach as is seen in monogastric animals like the dog and cat
Cattle:
What is fed to cattle varies widely, and nutrition for cattle varies with life stage such as growth, gestation, and lactation.
- Forage: Grass or hay
- Vitamins and Minerals: Delivered in the form of a loose mineral or a solid form. Solid products include a lick block that is made from salt and minerals compressed into block form. Supplemental vitamins and minerals are critical in grazing cattle to decrease the incidence of diseases.
- TMR (Total Mixed Ration): Balanced diet delivered to dairy cattle
- Composed of vitamin and mineral mix, protein mix, grains, and forages
- Advantages of a TMR is that each mouthful is the same, so the cows cannot pick out things they don’t like, which would risk nutritional deficiencies
Figure 8.32 Close-up image of hay
Sheep/Goats:
Nutrition will vary with life stage. For most goats and sheep, nutrient requirements can be met by available pasture, a mineral supplement, and water. During times of limited forage availability or quality such as winter, a supplement is needed to supply deficient nutrients.
The level of supplemental feeding should be adjusted with changes in animal requirements, such as the increased needs of late pregnancy. Sometimes dairy goats are fed grain to make up for energy losses from lactation.
Horses:
Horses are herbivores with a forage-based diet. They are grazers that should eat numerous small meals throughout the day. Horses are hindgut fermenters, which means that the majority of fermentation happens in the cecum. The hindgut processes plant components that do not get broken down in the small intestine. A huge resident microbial population is responsible for digestion of fibrous matter and includes bacteria, fungi, and protozoa.
Horses may eat for up to 18 hours per day. Continuous grazing maximizes saliva production and decreases risk of gastric ulcers and colic.
Horse feed can be classified into a couple different categories. Three of the major ones are shown below:
- Forage: Stems, leaves, and stalks of plants in pasture, and hay. Horses should consume at least 70% of their diets (ideally 80–100%) in forage.
- Grain: These are highly digestible with lots of carbohydrates. Can be used to supplement calories, vitamins, and minerals lacking in forage. Used frequently in high-performance horses.
- Salt and trace minerals: Salt should be provided free choice. Trace mineral blocks are available, but not always required.
Figure 8.34 Horse licking a salt block
Body Condition Score
The adequacy of a nutritional program can be assessed by observing changes in body weight and condition of the animal. If animals lose weight, body condition will be reduced (animal is thinner), letting us know there is a problem.
Body condition scoring: System of assigning a numerical score based on physical characteristics indicative of obesity. These include the amount of muscle and fat covering different areas of the body. Body condition scores range from 1, which is very thin, to 5, which is obese. Animals should achieve a certain body condition during specific periods of the production cycle.
Oftentimes, large animals’ body condition score is done on a scale of 1–5, while small animals like dogs and cats use a scale of 1-9. Therefore, it is important to always mark what the score is out of to avoid confusion, as 4/9 would mean ideal, while 4/5 is overweight.
Generally, on a 9-point scale 4 and 5 are ideal body weight, while 3 is ideal on a 5-point scale. This might differ slightly for production animals depending on what stage of the production cycle they are in.
How to: Body Condition Score
The following links give guides on how to body condition score a horse on both a 9 and a 5 point scale, and a cow on a 5 point scale. They will show you what to look for and where on the body we see notable changes.
It is important to actually palpate the animal when doing body condition scoring. This is especially important when it is difficult to visualize the areas of interest, such as in sheep, where everything is covered in thick wool.
Exercises
Attributions
Unless otherwise indicated, material on this page has been adapted from the following resource:
Root Kustritz, M. (2022). Veterinary preventative medicine. University of Minnesota. https://pressbooks.umn.edu/vetprevmed/, licensed under CC BY-NC 4.0
References
Kustritz, M. R. (2022a). 10. Nutrition: Basics. In Veterinary Preventive Medicine. University of Minnesota. https://pressbooks.umn.edu/vetprevmed/chapter/chapter-10-nutrition-basics/
Image Credits (images are listed in order of appearance)
Hay close-up by Renée Benczik. Used with permission.
Dairy barn TMR by Renée Benczik. Used with permission.
Horse licks salt in the Altai Mountains by Alexandr Frolov, CC BY-SA 4.0.
White horse grazing on pasture by Serafettin Ünye, Pexels licence.
Hay bale by Tiia Monto, CC BY-SA 3.0.
Key areas of a cow for BCS assessing by Huang, X., Hu, Z., Wang, X., Yang, X., Zhang, J., & Shi, D., CC BY.
