Properly balanced nutrition can affect the reproductive soundness of your herd
This paper lists some important nutritional considerations to optimize reproductive efficiency
There are no nutrients specifically required for reproduction which would not be needed for other physiological functions. Reproduction requires most of the same nutrients that are essential for maintenance, growth and milk secretion. Nutritional factors that cause reproductive failures or reduced efficiency will also have detrimental effects on other physiological functions, especially when deficiencies become more pronounced. There are few specific nutrients that will, in themselves, correct reproductive problems in goat rations that are balanced to meet general nutritive needs. The following paragraphs cover some of the most important nutritional factors influencing reproduction.
Many reports indicate that fertility is impaired by drought seasons, poor pastures, change to lower quality feedstuffs, conditions which produce lower feed intake, high production (of offspring or milk) which exceeds energy supplies and just plain underfeeding. An increase in energy supply is often followed by improved rates of ovulation and conception. This phenomenon of "flushing" has long been utilized by sheep breeders to increase lamb crops and is equally successful in goats. A lack of energy, i.e. supply below the required level of maintenance plus pregnancy, affects kid survival, the level of milk production and lactation length.
Energy supplies have a marked effect on age of puberty and thus on age of first kidding. Early breeding to reduce cost of replacements requires sufficient size of doelings at first estrus cycles, which means a moderately high level of energy in the doeling rations. Insufficient size of doelings at breeding may be followed by kidding problems five months later. Excess energy may also be detrimental physiologically by producing heavier doelings and reducing conception rates. This may happen to doelings on the show circuit where they tend to receive excess attention followed by a generous amount of feed. Actually, many goat exhibitors realize too late that judges do and should discriminate against overconditioning of doelings.
Pregnant doelings need extra energy not only for their pregnancy, but also to continue their growth rate sufficiently. Shortages of energy, especially under range conditions, are known to cause not only stunted growth but also abortion in goats. This occurs mostly between 90 and 110 days of gestation when undernutrition is especially critical to normal fetal development. So-called stress abortion is triggered by low maternal blood glucose levels which cause hyperactivity of the fetal adrenal gland. This results in elevated abortifacient estrogen levels and the premature expulsion of the fetus. After 110 days of gestation, the fetal adrenal is slower acting. However, maternal hyperadrenalism can also stem from undernutrition and low blood glucose resulting in dead or autolyzed fetuses. Thus, abortion can often be prevented by sufficient nutrition because many fertility problems can be considered a temporary reaction to a negative energy balance.
The relationship of protein to reproduction is similar to that of energy and the two nutrients interact to a large extent. Even when energy supplies are adequate, a shortage of protein will impair fertility, cause delayed onset of puberty, lengthen anestrus of goats and result in weak expression of estrus if it occurs. Additional protein requirements for goats during the late stages of pregnancy have been recommended by the National Research Council at levels equal to the nutritional needs for producing 2.5 lb of milk at 4.0% fat per day. On the other hand, excessive protein is not only an economic waste but feeding is costly and can lead to posthitis or sheath-rot in male goats, especially those in confinement.
Phosphorus and Vitamin D
A phosphorus deficiency is more likely than a calcium deficiency in grazing goats because of phosphorus deficient forages. Adequate phosphorus supplementation for high producing dairy goats is critical. A level of 0.4 % P in the total ration is recommended. The ratio of calcium to phosphorus should not be much different from 1.2:1.0. Excess dietary phosphorus has been associated with the occurrence of urinary calculi, particularly in confined bucks. In such cases a Ca:P ratio of 1.5:1.0 or greater is recommended.
Reproductive problems such as low first service conception rates and silent heats have been related to wide Ca:P ratios and to phosphorus deficiencies. Vitamin D has also been implicated through its effect on phosphorus utilization. Vitamin D supplementation is advised for young, poorly growing kids and goats in confinement and exposed to little sunlight.
Deficiencies of vitamin A or its carotene precursors or interference in their conversion are implicated in reproductive problems in goats, although more studies exist on cattle and sheep and species differences have been noted. Vitamin A is essential for normal spermatogenesis. It is also essential in combatting various respiratory and gastro‑intestinal diseases as well as parasites. Vitamin A is required for normal visual function, as well as healthy skin and mucous membranes. Protein deficiency in the feed, high energy rations, heat stress, phosphorus deficiency and presence of nitrates or nitrites in feed can interfere with proper vitamin A utilization or inhibit conversion of carotenes to vitamin A in goats. As a result, dead or weak kids may be born; even abortions or retained placenta may occur. Newborn kids may have low vitamin A reserves in the liver and suffer high mortality. Eye abnormalities are signs of more serious vitamin A deficiencies. This problem occurs more often during or after a dry summer. Green forages have abundant carotene supplies. Commercial supplementation of vitamin A is relatively inexpensive, as is that of vitamin D or E and all three are usually provided in commercial feeds in proper ratios, e.g. 5:1:0.01.
Selenium and Vitamin E
Retained placenta can be a selenium and vitamin E responsive disease when not caused by mechanical or pathogenic factors. Incidence of this problem can be markedly reduced with selenium and vitamin E treatment or supplementation, especially in those areas where the soils are selenium deficient. In the US, these areas include the East Coast, the Great Lakes region, New England, Florida, and the Northwest region. Selenium can be supplemented by feeding or injections. Deficiencies in growing kids can lead to white muscle disease. Vitamin E levels in goat milk are important as an antioxidant to extend shelf life. Specific vitamin E roles in improving goat reproductive efficiency have been alleged for some time, but reliable evidence is difficult to obtain.
Salt and Trace Elements
Lack of salt will reduce voluntary feed intake and lead to various deficiency symptoms including emaciation, the urge to lick and chew dirt, shaggy dull haircoat, poor growth and wobbly gait. Normally goats need between 5 and 18 lb of salt per year, depending on size and production level; and should have 1 % in their grain ration. Salt is also a convenient carrier for the trace elements needed by goats for normal reproduction. These trace elements are; zinc, manganese, iodine, cobalt, iron, copper and sulfur. Zinc and manganese in particular, affect spermatogenesis, libido and oogenesis when deficient. Goats appear to be different in the metabolism of many trace elements from cattle and sheep, e.g. iodine, iron, copper, molybdenum, but few studies exist involving goats. Young kids appear to be born with very low iron stores and are in early need of supplementation which can not come from goat milk. Multiple feed supplies and liberal browsing and grazing should produce few trace‑element deficiencies except under high production conditions.
Properly balanced nutrition can affect the reproductive soundness of your herd. Evaluation of the reproductive performance in your goat herd should include both the does and bucks. Protein and energy are important in conditioning of the doe and buck, while vitamin and mineral supplementation can address healthy eggs and sperm. A veterinary consultation can also aid in establishing a proper, up to date vaccination program designed to address any reproductive problems associated with viruses or disease.
Maryland Small Ruminant Page
International Goat Association