Maternal nutrition, fertility, and reproductive performance in the preindustrialized world.
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The flat-mite Brevipalpus phoenicis (Geijskes, 1939) (Acari: Tenuipalpidae) is considered important in citrus (Citrus spp.) and coffee plants (Coffea spp.) in Brazil, and is known as the leprosis and coffee ring spot mite, as being a vector of the Citrus Leprosis Rhabdovirus - CitLV and Coffee Ring Spot Virus - CoRSV. The objective of this work is to find out about the reproductive success of B. phoenicis on citric fruits and coffee leaves by fertility life table parameters and its biology. The experiments were carried out in laboratory conditions at 25 +/- 2 degrees C, 70 +/- 10% of relative humidity and 14 h of photophase. The lengths of embryonic and post-embryonic periods were different due to the host where the mite was reared. B. phoenicis showed better development and higher survival and fecundity in citric fruits than coffee leaves. The intrinsic rate of the population increase (r(m)) was 0.128 and 0.090 - females/female/day on citric fruits and coffee leaves, respectively. The citric fruits were more appropriate for the development of B. phoenicis than coffee leaves.
A 10-y history of high rates of perinatal deaths and congenital anomalies in dogs in a Shetland Sheepdog kennel prompted investigations into the cause(s). Skeletal fluorosis (mottled teeth in pups, bony exostoses in adults) followed use of a commercial dog food later found to contain 460 ppm fluoride (F) from rock phosphate added as a mineral source. The effects of the water source and fluoride in dog food on female reproduction and teratogenicity were investigated in a 2-y, 2-way factorial study in the kennel. Twenty adult shelties of proven fertility were brought into the kennel and randomized into 4 treatment groups, each consisting of 4 females and 1 male. Treatments were: Group A, high F (460 ppm) dog food, well water; Group B, high F dog food, distilled water; Group C, low F (55ppm) dog food, well water; Group D, low F dog food, distilled water. Only Group C produced as many pups as expected. Overall the missed pregnancy rate (44%) in study bitches and perinatal death rate (50%) in 48 study pups paralleled the problems in shelties resident in the kennel. Higher rates for both variables in the high F and the distilled water groups seemed likely due to chance. The only major anomaly was in Group D; minor anomalies appeared in all groups. Although 460 ppm F in dog food did produce bony exostoses, we did not find convincing evidence that it adversely affected reproduction in shelties. The cause of the reproductive problems was apparently not the dog food, water, foliage, genetic factors, or infectious disease and currently remains undetermined.
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The bacteriological status of the uteri of 150 cows was examined on 14 large-scale dairy farms 10 to 20 d after parturition and then twice again in 2-wk intervals during uterine involution. The degree of bacterial contamination and the proportion of the infected uterus as well as the composition of the isolated flora were determined. The antibiotic sensitivity of the important bacterium strains was also studied. The relationship between the reproductive data and bacterial contamination of the uteri was analyzed, and the influence of certain environmental and genetic factors on the rate of infection was examined. The proportion of cows having moderate or more serious uterine infection remained above 30 % at the end of involution on more than 35 % of the farms. Infections were caused mainly by streptococci, E. coli and corynebacteria. The bacterium strains showed broad resistance against commericially available antibiotics. There were significant differences in the length of time from the parturition to the first insemination and conception among cows at the various farms. There was a significant correlation between these differences and the bacteriological status of the uteri. Reproductive data were the lowest in the group of cows infected with Corynebacterium pyogenes. The rate of the infected uteri was considerably higher after the third parturition and in cows producing less than 20 l of milk per day. No connection was found between the bacteriological status of the uteri and the breed, type of housing, and season of the parturitions.
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Records (2263) from a single north Florida herd for 3 yr were evaluated in a series of analyses. Environment was subtropical. Data set included only cows that had normal milk records and became pregnant. Holsteins and Jerseys averaged 6799 and 4504 kg milk, 587 and 418 kg postpartum body weight, 164 and 141 days open, and 2.3 and 2.1 services per subsequent pregnancy. Pooled within breed, repeatabilities and heritabilities of these performance measures were .37, .15; .53, .25; .20, .06; and .30, 0. Estimable genetic correlations were milk yield and body weight -.09, milk yield and services per conception .38, and services per conception and body weight .37; range of standard errors was .22 to .39. Substantial genetic antagonism may exist between milk yield and body weight, and efficient reproduction. If results of this research are verified elsewhere, breeders should be aware that selection for increased weight could lead to decreased reproductive efficiency.
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Young female rats were made riboflavin-deficient by feeding a purified diet containing casein (210 g/kg). This basal diet provided 0.40 mg riboflavin/kg diet, to which was added additional riboflavin at 0, 0.12 or 0.25 mg/kg diet. Control animals received the same diet with 15 mg added riboflavin/kg. The diets were given for 4 weeks before mating, then throughout pregnancy and for 15 d of lactation. With no added riboflavin in the diet, reproduction was severely impaired and fetal resorption was usually observed. With 0.12 mg added riboflavin/kg diet, however, reproduction was usually successful, and the growth of dams and pups was only marginally depressed in comparison with pair-fed controls optimally supplied with riboflavin. The activation coefficient (stimulated:basal activity) of erythrocyte glutathione reductase (NAD(P)H) (EC 1.6.4.2) was high, and the concentration of riboflavin in the liver was correspondingly low in the dams receiving diets containing 0.12 or 0.25 mg added riboflavin/kg and in their sucking pups at 15 d post partum. Riboflavin levels in the milk from both groups of dams were about eightfold lower than in controls. There was little evidence that the sucking pups could maintain their riboflavin level at the expense of that in the maternal tissues.
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Incidence of retained placenta in dairy cows was evaluated in 627 parturitions. The herd was divided prepartum into three groups: 1) control, no treatment (n = 217 cows); 2) cows injected intramuscularly (n = 190) 21 to 10 d prior parturition with 45 mg Se and 2040 IU of vitamin E; and 3) cows intraruminally administered (n = 220) with two 30-g pellets containing 10% elemental selenium 2 mo prior to expected calving. Incidence of retained placenta (22.1%) was not reduced by Se in combination with vitamin E injection or intraruminal Se pellet nor were other measures of reproduction improved for cows fed a prepartum diet adequate in Se. At parturition the blood plasma Se concentrations were higher in treated postpartum with Se than in untreated cows. No difference in blood plasma Se was observed at parturition between cows with or without placenta retention. Cows dosed intraruminally with Se had a significant increase in milk Se, but this was too small to be a danger to human health. The present results on placenta retention suggest that this disorder is not a Se responsive disease in the dairy cow.
The purpose of this article is to provide considerations that must be included in a production medicine program. Although no two programs are the same, each of these areas must be addressed to be effective. Use of current knowledge and technology as well as emerging knowledge and technology to provide input into management practices for enhancing performance is the underlying goal of any production medicine program. The veterinary practitioner can serve as a participant in establishing and maintaining such a program as part of the complete management team.
The effects of injecting prostaglandin F2 alpha (PGF) in dairy cattle within 40 days of calving on the rate of pregnancy at first service and on the number of days open were investigated by meta-analysis, by pooling data from numerous independent trials into single analyses. A total of 4052 cows from 24 trials described in 10 papers were included in the analyses of first service pregnancy rate and 2646 cows from 21 trials described in nine papers in the analyses of the number of days open. The analyses were stratified by trial and by the reproductive health of the cows after calving. Treatment with PGF during this early post partum period had no significant effect on the first service pregnancy rate of cows with a normal or abnormal puerperium. An analysis of the data for the number of days open by effect-size methods showed that a significant percentage (54 per cent) of the treated cows had fewer days open than the untreated cows, and that this difference tended to be greater for cows with an abnormal puerperium (59 per cent of treated cows). The weighted average reduction in days open between the treated and control cows was 2.6 days for trials with abnormal cows, and 3.3 days for trials including normal and abnormal cows. However, the calculation of the fail-safe number (F) indicated that it would require only a few studies with a negative response to PGF to negate this finding. Meta-analysis was a useful technique for evaluating the apparently conflicting results of previous studies.
Data of 2779 purebred and crossbred heifers collected from five research stations of Agriculture Canada were used to study additive and nonadditive genetic effects on ages at first heat and at first breeding and conception rate at first service. Of these heifers, 2378 heifers had information on ages at first conception and at first freshening, days from first service to conception, and gestation length. The model included station, year of birth, sire, breed additive, maternal, and heterosis effects where sire effects were treated as random. Station differences were a significant source of variation for all reproductive traits. Year of birth had significant effects on four of seven reproductive traits. Breed additive effects for all genetic groups were not significant except for Finnish Ayrshire and American Holstein. No significant maternal effects were detected. Of 21 combinations of heterosis effects, six combinations showed significance. Partial regression coefficients ranged from negative to positive, suggesting that breed additive, maternal, and heterosis effects could increase or decrease for each percent increase of genetic contribution, depending upon the trait, breed group, and type of inheritance.
Forty-three purebred Holstein cows were put on an rbST milk production trial. There were 15 control cows (saline-injected), 15 cows injected with 10.3 mg rbST/d and 13 cows injected with 20.6 mg rbST/d. Injections were initiated between wk 4 and 5 of lactation and continued for 266 consecutive days. Fourteen of the rbST-treated cows were treated with one of three dosages of rbST in the previous lactation (10.3, 20.6, or 41.2 rbST/d). The objective of this study was to determine the health and reproductive efficiency of cows treated with rbST for up to two consecutive lactations relative to control cows. The incidence of 11 health-related variables before, during, and after the 38-wk injection period were not different among treatment groups. Previous treatment with rbST had no effect on reproductive variables; however, there was evidence that injections with the highest dosage of rbST in the current lactation resulted in lowered reproductive efficiency. It is possible that the effects of rbST on early lactation energy and nitrogen balance have confounding effects on the estrous cycle.