Optimal Reproductive Performance Research Articles

Energy utilization in pregnant and lactating sows: modeling of energy requirements.

Data on energy metabolism and body composition changes of the pregnant and lactating sow have been considered in order to propose methods for determination of energy requirements according to a factorial approach. Daily requirements for maintenance at thermoneutrality amounts to about 105 and 110 kcal ME/kg BW.75 in pregnant and lactating sows, respectively. During pregnancy, maintenance represents 75 to 85% of the total requirements and is affected greatly by environmental temperature and activity of the animals. Requirements for total uterine gain are low, but they increase with advancement of pregnancy. In addition, the daily ME requirements during pregnancy depend on the amount and composition of maternal weight gain and on the previous lactation body weight loss. The factorial approach indicates clearly that daily ME recommendation in pregnant sows varies from 6 to more than 10 Mcal and must be adapted to each sow within a herd. A method for prediction of ME requirements in lactating sows that considers a relatively precise estimate of energy output in milk is proposed. Results indicate that daily ME requirements are particularly high (15 to more than 20 Mcal) and generally are not met by voluntary feed intake. Emphasis also has been given to prediction of body composition changes that occur over the reproductive life of the sow. Data from the factorial approach allow for optimization of sow energy nutrition to ensure a normal evolution of body weight changes and to avoid major changes in body weight and composition. However, no available data demonstrate whether such a strategy is concomitant with optimal lifetime reproductive performance.

Relationship Between Nutrition and Reproduction in Beef Cattle

The primary nutrient consideration for optimum reproductive performance in beef cattle is energy. Low energy intake delays the onset of puberty in heifers and bulls. Heifers should reach approximately 66 per cent of mature body weight by 14 to 15 months of age and be bred 30 days prior to breeding the main cow herd. Body conditioning scores (BCS) (1 = emaciated, 9 = obese) should be used to evaluate pregnant cows entering their third trimester. Cows should calve with body conditioning score 5 to 7. Forage quality and environmental factors influence maximum dry matter intake and nutrient requirements and must be considered in the clinical setting. Crude protein dietary content should be 11 to 12 per cent for lactating beef cattle. Mineral (calcium, phosphorus, magnesium, potassium, sulfur, sodium, chloride) nutrition is not a major cause of decreased reproductive performance in beef cattle. Trace mineral deficiencies (particularly selenium, copper, and zinc) can cause decreased reproductive performance. Diagnosis of these trace mineral deficiencies can be confirmed by elemental analysis of blood or tissues.

Seasonal variation in cowpea crop performance at Ile-Ife, Nigeria and the relationship to insect damage

The trends in flowering, podding and seed yield of four cowpea varieties planted at different times of the growing season in 1975 and 1976, were studied along with the associated pest activity. Flowering, podding and seed yield were found to decrease over the season from April to September irrespective of whether the crop was protected against insect pests or not. However, there seemed to be two peak periods of pest activity—April to July and October to December—when severe damage to the crop occurred in unprotected plots. Planting in June or July usually led to an escape from several major pests even though the cool night temperatures and incidence of overcasts at that period seem to preclude optimal reproductive performance of the crop. The pattern of insect pest succession on the crop over the season is discussed and it is suggested that for small farm holders in Southern Nigeria, who are unlikely to apply insecticides, planting in June is advisable.

THE EFFECT OF FOUR DIFFERENT TYPES OF FLUORESCENT LIGHT ON GROWTH, REPRODUCTIVE PERFORMANCE, PINEAL WEIGHT AND RETINAL MORPHOLOGY OF YORKSHIRE GILTS

Fifty-seven, 110-day-old Yorkshire gilts were housed in 16 basement pens to study the effect of four types of fluorescent light upon growth, puberty, ovulation rate, fetal number, fetal sex ratio, pineal weight and the retina. Gilts exposed to red light achieved puberty later (P < 0.01) and at heavier weights (P < 0.05) than gilts exposed to cool white light, full spectrum daylight, or ultraviolet light. Each gilt was exposed to a photoperiod of 16 h of one light source, with 8 h of darkness daily. Average weights and ages at puberty were 104.5, 99.9, 99.7 and 97.7 kg and 192.1, 177.2, 181.5 and 179.9 days, respectively. Heavier pineal glands (P < 0.05) were also observed in the gilts exposed to red light, indicating that a heavier pineal gland may be associated with delayed puberty. In addition, there was a significant trend (P < 0.01) across all treatments for the older animals to have heavier pineal glands at slaughter. Significant differences attributable to the four lighting treatments were not noted in average daily gain or feed efficiency. When the gilts were slaughtered, at not earlier than day 40 of gestation, no significant differences were found in ovulation rate, fetal number and fetal sex ratio between treatments. A histological investigation of the retina from the gilts did not reveal detectable damage due to the ultraviolet light or other light treatments. It is concluded that the gilts were responsive to those regions of the light spectrum below red. Cool white fluorescent light appears to be the most economical fluorescent lighting for maintaining optimum growth and reproductive performance in the breeding herd. Key words: Light spectrum, photoperiod, growth, puberty, pineal gland, retina

CHOLINE SUPPLEMENTATION OF BARLEY-WHEAT-SOYA DIETS AND THE REPRODUCTIVE PERFORMANCE OF SWINE

The effect of choline supplementation (434 mg/kg of diet) on reproductive performance and incidence of spraddle leg condition in baby pigs was studied in two experiments, using 128 gilts (64 Lacombe + 64 Yorkshire) in exp. 1 and 64 primiparous sows and 64 gilts, half from each breed, in exp. 2. In exp. 1 (winter) supplemental choline significantly (P < 0.05) increased the number of live pigs born (9.64 ± 0.41 vs. 7.90 ± 0.31) and weaned (7.50 ± 0.68 vs. 6.73 ± 0.25) for Lacombe, but not for Yorkshire (8.40 ± 0.56 vs. 9.00 ± 0.45 and 7.40 ± 0.33 vs. 8.10 ± 0.33, respectively) gilts. The mean birth weights and weight gains to 3 and 5 wk of age were similar for the control and choline-supplemented groups. In exp. 2 (summer) choline supplementation had very little effect on reproductive performance of gilts or sows from either breed. The incidence of spraddle leg condition was very low in both experiments and was not influenced by choline supplementation. These results indicate that the choline content of barley-wheat-soya diets was adequate for reproduction in Yorkshire gilts and sows, but Lacombe gilts may require supplemental choline during winter for optimum reproductive performance.

Effects of Generation-Long Temperature Acclimation on Reproductive Performance of the Desert Pupfish, Cyprinodon n. nevadensis

The hypothesis was tested that the reproductive function would exhibit compensation to temperature if the organism was bred and reared at temperatures which ordinarily produced less than optimal reproductive performance. Desert pupfish, Cyprinodon n. nevadensis, were bred and the eggs reared at the optimum temperature for reproduction, 28 C, and at two marginal temperatures, 24 and 32 C. Each brood was divided into three groups and reproductive performance was tested at the rearing temperature and at two alternate temperatures to which they had never before been exposed. The eggs laid per spawning and eggs laid per gram body weight per day showed no compensation to rearing temperature. Reproductive performance was optimal at 28 C and was poor at both marginal temperatures, regardless of the previous thermal history of the fish. Lower egg viability at 32 C was associated with a thin egg coat, small yolk diameter, and low gonosomatic index as compared with the same measurements at the lower temperatures.

The Effect of Pen Floor-Type, Environmental Temperature, and Dietary Calcium Source on the Reproductive Performance and Blood Calcium of Medium White Turkeys

This experiment was designed to study the effect of: 1) environmental temperatures of 13, 21, and 28 C, 2) laying cages vs. litter floors, and 3) limestone flour vs. oyster shell flour on the reproductive performance and blood calcium levels of turkeys.Feed consumption was significantly reduced as the environmental temperatures increased. No significant differences were obtained in egg production, settable eggs, egg weight, fertility, hatchability, or body weight within the range of pen temperatures studied. Post-lay whole blood and plasma calcium levels were lower in females held at 28 C.The difference in egg production among females in cages and on litter floors was not significant. Females in cages produced a lower percentage of settable eggs than those on litter floors and had lower post-lay total plasma calcium, whole blood calcium, and hatchability. Fertility of the caged hens and of those on litter floors was 77.0 vs. 83.3%, respectively. A sample of eggs was broken out and examined macroscopically. Results indicated a reduction in true fertility due to the cage environment. Feed consumption and body weights were similar for both pen types.Oyster shell substitution for limestone yielded better shell quality as determined by the percentage of settable eggs and by egg shell breaking strength. However, first-order interactions indicated that the effects were somewhat dependent on the temperature-floor treatment combination. No differences were found in blood calcium levels between the two calcium sources.These results showed that the reproductive potential of the egg production lines of turkeys utilized in the present study was not adversely affected by environmental temperatures as high as 28 C and that litter pens resulted in optimum reproductive performance.

A Study of Certain Environmental Factors and Mineral Chelation on the Reproductive Performance of Young and Yearling Turkey Hens

The study presented was designed to determine the effects of laying cages and conventional litter floors, pen temperatures of 12.8°, 21.1° and 29.4° C, and chelated (EDTA-Zn) vs. nonchelated trace mineral mixes on the reproductive performance of yearling force-molted and young Large White female turkeys.Reproductive performance, as measured by egg production, settable eggs, fertility and hatchability of fertile eggs, was not significantly different between young and yearling hens. Females fed a chelated trace mineral mix had a higher percentage of settable eggs, greater feed consumption and thicker egg shells. Females in laying cages laid at a higher rate, ate more feed, and weighed more than those on conventional floors. Significant differences were not observed between the two pen environments for hatchability of fertile eggs or egg weight. The percentages of settable eggs and of fertile eggs were lower when females were maintained in cages.A constant temperature of 29.4° C. reduced egg production below that obtained from females maintained at 12.8° and 21.1° C. The high pen temperature also caused lower body and egg weights, more birds out of production and an increased incidence of molting. Feed consumption decreased with increasing pen temperatures. Fertility, hatchability, percentage of settable eggs and egg shell thickness were unaffected by the imposed temperature environments. Temperatures of 12.8° and 21.1° C. yielded comparable results for all reproductive parameters measured. Within the range of temperatures studied, results obtained suggest that optimum reproductive performance can be obtained with breeder turkeys when environmental temperatures are maintained between 12.8° and 21.1° C.

EFFECTS OF DIETARY VITAMIN A ON GROWTH AND REPRODUCTION IN RABBITS

Twenty-four, 4-week-old rabbits were fed diets to provide 0, 3, 6, and 12 μg vitamin A per kg bodyweight per day. After 17 weeks, rabbits on the 0 level exhibited significantly lower feed intake and growth rate and all six animals died before the completion of the 24-week feeding period. The six rabbits on the 3-μg level developed ocular lesions and five died before the completion of the trial. Avitaminosis A was less prevalent on the higher levels with no deaths on the 12-μg diet. Reproductive performance of a surviving male continued on the 3-μg level was characterized by absence of spermatogenesis. Mature males placed on the same ration did not exhibit decreased reproductive function. Reproductive performance of surviving females was directly related to vitamin A level. Offspring from females on the 3-, 6-, and 12-μig levels all exhibited avitaminosis A with per cent surviving 14 days at 0, 15, and 59, respectively. Minimal daily vitamin A requirement for young growing rabbits and breeding males would appear to be approximately 8 μg/Wkg whereas a vitamin A intake in slight excess of 14 μg/Wkg was inadequate for optimum reproductive performance in female rabbits.

SIMPLIFICATION OF HIGH WHEAT DIETS FOR LAYING HENS: VALUE OF SUPPLEMENTATION WITH METHIONINE HYDROXY ANALOGUE

Groups of laying strain pullets were maintained singly in wire cages and fed a diet in which rolled, feed grade, hard red spring wheat was the sole cereal grain and no protein supplement was added. For other groups this diet was supplemented with 5, 10, or 15% soybean meal, or 2% blood meal. A further treatment consisted of replacing 10% wheat with soybean meal and using one-half wheat and one-half corn as the cereal portion of the diet. All of the above diets were fed in the absence of amino acid supplementation and in the presence of methionine hydroxy analogue (MHA). The duration of the experiment was eight periods of 28 days. The results suggested that with a simplified diet based on wheat and soybean meal, between 10 and 15% soybean meal was necessary for optimum reproductive performance. The supplement of MHA improved performance only in diets where total protein or lysine, or both, was/were not first limiting. The simplified diet containing 87.25% wheat, 2% blood meal, and 0.125% MHA supported a rate of egg production of 68%, clearly demonstrating the extent to which wheat might be used with further slight modifications of the diet.

Effects of Space Restriction and Management on Pre- and Post-Puberal Response of Female Swine

Confinement management practices and environments required for optimum reproductive performance in swine have not been determined. Robson (1966) and England and Spurr (1969) have observed that gilts that were tethered (restrained by a neck collar and chain) or in individual pens showed more erratic estrous and mating behavior than similar gilts confined in groups. Farrowing performance, however, among treatments was similar. Others (Warnick et al., 1965; Teague, Roller and Grifo, 1968; Edwards et al., 1968) have reported that exposure to high ambient temperatures can delay onset of estrus, decrease percent conception and increase embryonal death. The present study was initiated to evaluate the effects of space restriction and certain environments on age at puberty, ovulation and conception rates, and embryo number and survival at 20 to 31 days after mating.

Protein and Energy Interrelationships for Laying Hens

PROTEIN × energy interrelationships for optimum reproductive performance of chickens have been discussed by Thornton and Whittet (I960), Frank and Waibel (1960), and Touchburn and Naber (1962). Considerable evidence has appeared in literature to indicate a disparity regarding protein × energy interrelationships, and Harms (1964) has attempted to discuss the reasons for the discrepancies.A majority of studies on protein × energy interrelationships involved Single Comb White Leghorns, or Leghorn-type strain crosses, and in many cases, what was considered a low energy level by one investigator was considered a high energy level by another investigator. For example, the low and high energy values of Frank and Waibel (1960) ranged from 634 to 947 and from 984 to 1250 kilocalories of productive energy per pound, respectively, as contrasted with a low and high energy level of 640 and 930 kilocalories of productive energy per pound, respectively, (Miller et al., 1957).Therefore,…

Influence of Lysine Supplementation on the Reproductive Performance of Turkey Breeders

Abstract THERE is a limited amount of experimental data available on the protein level required by turkey breeders for optimum reproductive performance. Protein requirements varying from 15 to 22 percent have been reported. Atkinson et al. (1960) reported that higher egg production and best feed efficiency were obtained with turkey breeder diets containing 22 percent protein. Carter et al. (1957) found that fertility and hatchability were slightly better with higher protein levels. They compared 16 and 18 percent protein in combination with productive calorie levels of 800, 900, and 1,000 per pound. Robblee and Clandinin (1959) found no advantage for using a 17 percent protein diet over a diet containing 15 percent. Jensen and McGinnis, (1961) using rations as low as 10 percent protein observed no protein deficiency symptoms. They felt that 15 percent protein was adequate for the turkey hen. The difference in protein requirement reported by these authors many…

Nutritional Investigations with Turkey Hens : 2. Requirement for Unidentified Factors

DURING the past decade, workers at the Texas Agricultural Experiment Station have published reports showing that turkey breeder hens require certain dietary unidentified factor supplements for optimum reproductive performance (Atkinson et al., 1951, 1953, 1955; Ferguson et al., 1956; Feldman et al., 1957; and Whiteside et al., 1960). Addition of such supplements as dried brewer’s yeast, condensed fish solubles, fermentation residue, and dehydrated alfalfa meal to a milo-corn-soybean oil meal basal diet, markedly improved hatchability of fertile eggs, (Whiteside et al., 1960).An experiment to study the effect of adding several unidentified factor supplements to a corn-soybean oil meal diet on the performance of Broad Breasted Bronze hens is reported in this paper. EXPERIMENTALTwelve pens of 10 Broad Breasted Bronze turkey hens in an enclosed house with mechanical ventilation were used. The birds had been on a protein requirements study (Jensen and McGinnis, 1961). For eleven weeks, they were…