Comparing to sheep and cattle, according to their diet, goat species are considered as intermediate feeders (Hofmann, 1989). Goats change their feeding behaviour according
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to seasonal changes in diet availability (Fedele et al., 1993; Papachristou, 1994). Goats are characterised by high saliva secretion and large absorption surface of the rumen epithelium, which protect them from the risk of acidosis; and by their considerable enlargement of the digestive apparatus when highly fibrous feed is used (Silanikove, 2000). Goats are selective . Indeed, more than other species, goats are able to choose, among the available feedstuffs, parts of plants with the highest protein content and the highest digestibility. They select feed on the basis of prehension ease, sensorial characteristics and post-ingestive effects learnt from their own experience (Provenza et al., 2003).
Feed intake is related to breed, feeding conditions and livestock system. According to Avondo et al. (2008), feed intake of Girgentana lactating goats increased (up to 3 kg DM per day) with self-regulating crude protein (16.5%) and neutral detergent fibre (34%).
Economides (1998) and Fedele et al. (2002) demonstrated that even diets of 60-70%
concentrate levels, goats do not alter their productive capacity or their metabolic well- being. According to Abijaoudé et al. (2000), when a diet is rich in concentrate and may cause metabolic effects, goats change their feeding behaviour and reduce daily feed intake to avoid dangerous effects of excessive starch in the rumen.
2.5.1 Dry matter intake of goats
The daily feed intake of goats ranges from 3-4% of body weight and is influenced by dry matter of feeds (which range from 12-35% in forages, 86-92% in hays and concentrates), palatability, and physiological stage of the goats (growth, pregnancy, and lactation) (Rashid, 2008). However, to meet the production (milk or meat) purpose, nutrients are required depending of age, sex, breed, body size, climate and physiological stage of the animal. The six classes of nutrients are protein, carbohydrate, fat, vitamins, minerals, and water. Nutrients are often classified as organic (carbon-containing) or inorganic (minerals, water).
14 2.5.2 Nutrient requirements of goats
To meet energy, protein, mineral, and vitamin requirements of goats, feeding strategies should be used depending on the condition of the goats. Energy is derived from the breakdown of several nutrients, including fat, protein, and both simple and complex carbohydrates. Energy and/or protein deficiencies cause weight loss and low productivity of animals, and oversupply of these nutrients will usually result in excessive fatness, which is also undesirable.
2.5.2.1 Nutrient requirements of lactating does
When feeding goats to meet their maintenance and production requirements, the primary goal is to maintain body weight and subsequently satisfy production. Nutritive elements should satisfy doe requirements in order to reach the expected production. Lactating does need nutrients according to different stages of production and total digestible nutrients are required more than crude protein at any stage (Table 2.4).
Table 2. 4Nutrient requirements of mature does (Rashid, 2008)
Production stage Nutrient requirements, dry matter basis
DMI, % of BW % CP % TDN
Maintenance 1.8 - 2.4 7 53
Early gestation 2.4 - 3.0 9 - 10 53
Late gestation 2.4 - 3.0 13 - 14 53
Lactation 2.8 - 4.6 12 - 17 53 - 66
DMI: Dry matter intake; BW: body weight; CP: crude protein; TDN: total digestible nutrient
2.5.2.2 Nutrient requirements for early to mid-gestation
During this phase of production, the goal is to maintain body condition of mature females and increase condition of young females. Nutrient requirements are only slightly above maintenance; low quality feedstuffs should be utilized. Young females should be fed separately from mature females. Does do not need grain in early pregnancy. Overfeeding can lead to complications such as hypocalcemia and ketosis; pregnant goats can drink up to 16 L of water a day (Cheryl, 2012).
15 2.5.2.3 Nutrient requirements for late gestation
Late gestation is probably the most critical period for doe nutrition. Energy requirements increase dramatically in late pregnancy (Hart, 2008; Susan, 2008). Does gain body weight during this phase. Seventy percent of foetal growth occurs during this period. Mammary tissue is also developing. Proper nutrition is necessary to prevent pregnancy toxaemia (ketosis) and milk fever (low blood calcium). Nutrition affects the birth weights of kids and a higher mortality among small and large kids occurs when nutrient requirement are unbalanced. On the other hand, when feeding more than the requirements, oversized foetuses increase dystocia incidences.
2.5.2.4 Nutrient requirements for early lactation
Feeding lactating does is related to their genetic potential for milk production and desired level of production. There is a little or no reason to increase the feeding levels of does that have just given birth. Does that have been properly fed in late gestation usually produce more than enough colostrum for their kids. In this phase, it is reasonable to provide does with fresh and clean water permanently and forage only for a few days.
When lactation advances, nutritional requirements increase to their highest and especially if they are nursing multiple kids. Feed should be provided according to the number of kids.
2.5.3 Nutrition for kids
It is crucial that kids nurse their mothers (does) in the first 8 hours of their life to consume colostrum at a minimum rate of 10-20% of their body weight, preferably within 2-3 hours after birth (Rashid, 2008). Colostrum contains vitamins and antibodies that will save kids from many diseases including enterotoxaemia and tetanus. Growing kids have the highest protein requirements. Creep feeding may or may not be economical, especially for goats.
Energy needs depend largely upon desired growth rates and the animals' genetic potential for growth.
16 2.5.4 Nutritional complications in goats
2.5.4.1 Pregnancy toxemia (Ketosis or Twins disease)
Does need high energy diets during the last period of pregnancy especially prolific does to cover the needs of foetuses (Rashid, 2008). Malnutrition during the terminal weeks of pregnancy leads to the breakdown of body fat reserves that secrete ketones. Due to lack of energy the glucose concentration in the brain decreases and nervous signs appear. At this stage the doe seldom survives. Autolysis of dead foetuses produces toxins causing toxemia in the doe and eventually death (Rashid, 2008). Treatment is usually unsuccessful. Intravenous injection of 5% dextrose can be helpful in the early stages.
However, proper feeding of does during pregnancy can prevent pregnancy toxemia.
2.5.4.2 Acidosis, enterotoxemia, founder and hypocalcemia
A sudden increase or excessive feeding of grains can also cause healthy problems to the doe. Lactic acid content of the rumen can increase to toxic levels (acidosis) due to feeding of starches that exceed need. Acidosis can cause vasoconstriction of blood vessels around hooves (founder). High levels of starch in the diet also speed up the bacterial growth in the intestines (Enterotoxemia). The rapid bacterial growth means more endotoxin production and death occurs quickly. This usually happens with rapidly growing kids.
Often called milk fever, hypocalcemia is a deficiency of calcium in the blood that arises when a doe does not get enough calcium in her diet to support its needs and the needs of unborn kids.