Goats are small ruminants that have similar nutrient requirements to dairy cattle. Many people mistakenly believe, however, that dairy goats can be fed the same way that dairy cows are fed. Goats are known as “opportunistic feeders” as they can change their feeding behaviors according to the season and diet availability. Especially on goat dairies that allow their goats to be out on pasture or browse, this can be problematic when determining if protein and energy are being underfed or overfed to meet a certain level of milk production.
Goats are unique among ruminants in that they have the ability to be selective as they eat, choosing their favorite vegetation and separating it from what they don’t want. Compared to cows, which tend to take large mouthfuls when they are eating, goats can browse and nibble on bushes and tree branches without having to consume the entire plant. Being able to adapt to a broad range of feeding conditions and forage types enables goats to self-regulate their protein and fiber intakes with minimal daily variations and rumen upsets. They are instinctively gifted in being able to avoid plants that may cause them metabolic problems and they will adjust their eating habits to smaller and more numerous meals during the day to keep their rumen stable.
A goat’s tendency to self-regulate nutrition and feed intake can make it challenging to get her to consume adequate feed each day to support more than a gallon of milk production at the onset of her lactation. Milk production is positively correlated to feed intake and nutrient absorption in ruminants. Compared to cow nutrition, managing a goat feeding program and feed quality can be more difficult and time consuming due to their fussy nature.
It takes about the same amount of energy to produce a pound of goat milk as it does cow milk. Being significantly smaller in size, though, goats consume only a fraction of the dry matter of dairy cattle, which makes them ideal for locations with limited land for agriculture. Goat milk is nutritious and, because the fat molecules are smaller than that of cow milk, goat dairy products are often recommended for people, including infants, who have difficulty digesting cow milk.
At the risk of offending some goat owners, goat dairies are still very much a cottage industry. Goat dairies run the gamut from being predominantly grazed herds with minimal grain and vitamin/mineral supplementation with low milk production per animal to large commercial goat herds seeking to maximize milk production with their goats confined to barns. As with all animal production systems, before diets can be formulated for milk production, a targeted level of milk production must be known.
A lactating doe must consume about 5 percent of her body weight in feed dry matter if she is producing about 1 gallon of milk. So a doe weighing 150 pounds will need to consume about 7.5 pounds of feed dry matter, of which the roughage to concentrate ratio should be about 50-50. Does producing up to 2 gallons of milk per day should be encouraged to consume 6 percent to 7 percent of their body weight in feed consumption on a dry matter basis.
The crude protein (CP) level in lactating goat rations should be between 16 percent and 18 percent. Formulating diets that meet this requirement depends on how much CP is in the hay or pasture that the goat has access to. If the hay or pasture is high in CP, 18 percent CP for example, the CP in the concentrate need be no higher than 18 percent to maintain a total diet CP of 18 percent. Unlike dairy cow diets, balancing for amino acids in goat diets is mostly ignored. However, from personal experience, feeding protein sources high in lysine, an important amino acid, will result in more milk production in goats.
If the forage is of low quality, perhaps only 10 percent CP, then the grain supplementation must be increased to 26 percent CP to balance the diet at 18 percent CP. If the goats have access to a variety of browse, there is an additional level of nutrient variation that may not be accurately measured. Diets for goats that are confined to barns or stalls and have little or no access to pastures or browse are easier to balance since forage and concentrate levels can be controlled. As with all ruminants, care must be taken that concentrates or low-fiber byproducts are not overfed.
Meeting dietary energy requirements for goats is also dependent on the quality of forages fed. Net energy requirements measured in megacalories (mcal) should be calculated separately for production. A doe weighing 150 pounds requires about 1.3 mcals of energy per day just for maintenance. Most grass forages deliver little more than 0.5 mcals/pound (dry matter basis). If a doe were to eat 4 pounds of this forage, her energy intake would be about 2 mcals – therefore exceeding her maintenance needs. The excess energy will be used for milk production, growth or pregnancy needs. Due to a goat’s high activity level, energy is often a limiting nutrient, especially in colder climates. Goats can quickly lose body condition when dietary energy is lacking.
Energy needed for milk production must be added to the maintenance requirement. Net energy needed to support a pound of milk at 4 percent butterfat is 0.32 mcals. If our doe is expected to produce 10 pounds of milk, she must consume 3.2 total mcals of energy. Add this to the aforementioned calculated 1.3 mcals needed for maintenance and the total is 4.5 mcals for milk production and maintenance. Additional energy must be factored in when does are pregnant. Energy needs for pregnancy require between 0.5 and 0.8 mcals, which now puts our total energy needs for a 150-pound pregnant doe producing 10 pounds of milk over 5 mcals of energy per day.
In practice, meeting the energy and protein requirements for dairy goats to produce over 1 gallon of milk per day is not difficult. Work with your nutritionist or feed company representative to formulate properly balanced diets for your goats. Most commercial feed mills produce pelleted feeds that meet the nutritional requirements for lactating goats. Knowing the weight of your goats and the expected levels of milk production along with their activity levels is critical in designing and formulating diets that will meet your expectations for milk production.