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NUTRITIONAL CAUSES OF REPRODUCTIVE LOSSES


COLLECTION: GOAT HANDBOOK
ORIGIN: United States
DATE INCLUDED: June 1992

Extension Goat Handbook

This material was contributed from collections at the National Agricultural Library. However, users should direct all inquires about the contents to authors or originating agencies.

DOCN 000000035
NO D-9
NUTRITIONAL CAUSES OF REPRODUCTIVE LOSSES
H. H. Van Horn; U. of Florida, Gainesville G. F. W. Haenlein; U. of Delaware, Newark
D. L. Ace; Pennsylvania State U., University Park
Genetics and Reproduction


1 It is important to realize from the beginning that 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 if goat rations are balanced to meet general nutritive needs as far as is known today.

2 The most important nutritional factors influencing reproduction are:

-Energy -Protein -Phosphorus and vitamin D -Vitamin A -Selenium and vitamin E -Salt and trace elements

3 Energy Many reports indicate that fertility is impaired in drought seasons, by poor pastures, change to lower quality feedstuffs, conditions which produce lower feed intake, high production (triplets, milk records) which easily exceeds energy supplies, and just plain ''hollow belly disease.'' 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 crop 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.

4 Energy supplies have a marked effect on age of puberty and thus on age of first kidding. Early breeding for better economics of raising replacements require sufficient size of doelings at first estrus cycles, which means a moderately high level of energy in the doeling rations. Insufficient size at breeding of doelings may be followed by kidding problems five months later. Excess energy is just as wrong physiologically since it fattens doelings unnecessarily and reduces conception rates besides being uneconomical. This may happen to doelings on the show circuit where they tend to receive an excess of attention that is followed by the feed scoop too generously. Actually, many goat exhibitors realize too late that judges do and should discriminate against overconditioning of doelings.

5 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 may occur 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 initiates hyperactivity of the fetal adrenal gland resulting in elevated abortifacient estrogen level and the premature expulsion of a live or fresh 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 be prevented by proper sufficient nutrition because most fertility problems can be considered to a large degree a temporary reaction to a negative energy balance.

6 Protein 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 requirements for protein for late stages of pregnancies of goats have been recommended by the National Research Coun ++++MISSING DATA++++ cil at levels equal to the nutritional needs of producing 2.5 lb of goat milk per day at 4.0 22568349762258770000000000000000000000000000000000 DATA++++

7 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 more critical. A level of 0.4P in the total ration is recommended. The ratio of calcium-to-phosphorus should not be much different from 1.2 : 1.0. Excess of phosphorus has been associated with the occurrence of urinary calculi, particularly in confined bucks; in which case a Ca:P ratio of 1.5 : 1.0 or greater is recommended.

8 Poor reproduction performance has been related to wide Ca:P ratios and to phosphorus deficiencies; such as low first service conception rates and silent heats. 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.

9 Vitamin A Deficiencies of vitamin A, its carotene precursors or interference in their conversion all 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 in quantity and quality. It is also essential in combatting various respiratory and gastro-intestinal diseases, and parasitism, and is needed for normal visual functions and healthy skin and mucal membranes. Protein deficiency in the feed ration, high energy rations, heat stress, phosphorus deficiency and presence of nitrates or nitrites in feed interfere with proper vitamin A levels 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 liver reserves and suffer high mortality. Eye abnormalities are signs of more serious vitamin A deficiencies. This can occur more during or after a dry summer, while green forages have abundant carotene supplies. Commercial supplementation of vitamin A is relatively inexpensive, as is that of vitamin D or E, which all three are usually provided in commercial feeds in proper ratios, e.g. 5:1 : 0.01.

10 Selenium and Vitamin E Retained placenta can be a selenium and vitamin E responsive disease when not caused by mechanical or pathogenic factors. That incidence can be markedly reduced with selenium - vitamin E treatment or supplementation, especially in those areas of the US where the soils are selenium deficient such as 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 kis and lambs can lead to white muscle disease. Vitamin E levels in goat milk are important as an antioxidant to extend shelf life and milk qualities in storage. Specific vitamin E roles in improving goat reproductive efficiency have been alleged for some time but reliable evidence is difficult to obtain.

11 Salt and Trace Elements Lack of salt will reduce voluntary feed intake and develop various deficiency symptoms besides emaciation, urge to lick and chew dirt, shaggy dull haircoat, poor growth and wobbly gait. Normally, goats need between 5 and 18 lb salt per year, depending on size and production level; and should have 1 0n their grain ration. Salt is a convenient carrier also for the trace elements needed by goats for normal reproduction such as 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.

NUTRITIONAL CAUSES OF REPRODUCTIVE LOSSES
COLLECTION;GOAT HANDBOOK
ORIGIN;United States
DATE_INCLUDED;June 1992


 
 


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