Biomedical subjects

R W Everett

Publications and source records attributed to R W Everett.

At least 19 recordsLinked to original sources

PubMed2000

Effects of inbreeding on production and survival in Holsteins.

Responses of registered Holstein cows to various levels of inbreeding were examined with pedigree data supplied by the Holstein Association USA and test-day production data from 1970 through 1998 obtained from the Animal Breeding Center at Cornell University. Rate of increase in level of inbreeding has been accelerating over time, making it more difficult for producers to make matings that avoid the potentially deleterious effects of inbreeding. Milk production losses per lactation caused by inbreeding were generally 35 kg per percentage inbreeding level >0.01 but increased to 55 kg per percentage inbreeding level from 0.07 to 0.10. Somatic cell score was not affected by level of inbreeding. Inbreeding had the greatest effect on production at ages <22 mo and early in lactation. Early onset of the deleterious effects of inbreeding resulted in larger net present value losses than when effects of inbreeding occurred later. Losses were likely enhanced due to the need to freshen animals as early as possible to maximize net present value returns. Survival decreased as level of inbreeding increased and was likely to have a greater negative impact on the financial health of the dairy enterprise than production losses.

Age Factors↗

PubMed2000

Effects of inbreeding on production and survival in Jerseys.

Responses of registered Jersey cows to various levels of inbreeding were examined with pedigree data supplied by the American Jersey Cattle Association and test-day production data from 1970 through 1998 obtained from the Animal Breeding Center at Cornell University. Rate of increase in level of inbreeding is accelerating with time, making it more difficult for producers to make matings that avoid the potentially deleterious effects of inbreeding. Production losses caused by inbreeding were significant and curvilinear for all traits studied except somatic cell linear score, with the greatest losses at higher levels of inbreeding. Inbreeding was found to have the greatest effect on production at early ages and early in lactation. Early onset of the deleterious effects of inbreeding resulted in larger net present value losses than if effects of inbreeding occurred later in the life of an animal. Losses were probably enhanced because of the need to freshen animals as early as possible to maximize net present value returns. Survival decreased as level of inbreeding increased and was likely to have a greater negative impact on the financial health of the dairy enterprise than production losses.

Age Factors↗

PubMed1999

Production responses to bovine somatotropin in northeast dairy herds.

The commercial response to bovine somatotropin was examined in northeast dairy herds from 1990 to 1998 (4-yr preapproval and 4-yr postapproval). With DHI records and Monsanto customer files, a control group (never purchased Posilac) and a bovine somatotropin (bST) group (used on at least 50% of cows) were identified. A total of 340 herds were involved and, over the 8-yr period, there were over 80,000 cows, 200,000 lactations, and 2 million test days. Herd management comparisons demonstrated the response to bST was relatively constant each year of the postapproval period. Assuming 100% of cows were supplemented, response to bST over a 305-d lactation equaled 894 kg of milk, 27 kg of milk fat, and 31 kg of milk protein. Comparisons of lactation curves were used to identify where the bST response occurred in the lactation cycle. Analysis demonstrated the responses in milk, milk fat, and protein yield were minimal in the early phase of lactation, and then gradually increased until reaching a plateau over the last half of the lactation cycle. Persistency of lactation was also improved by bST, indicating the opportunity exists to extend lactation with combined use of bST and altered reproductive management. Average age and days in milk did not differ between control and bST herds. Thus, stayability and herd-life of animals were not altered by bST treatment. Somatic cell count (SCC) linear scores were minimally affected in herds utilizing bST and the pattern of SCC over the lactation cycle was unaffected. Overall bST improved lactation yield and persistency consistently over the 4-yr postapproval period with no effects on cow stayability and herd-life.

Animals↗

PubMed1998

Effects of three prepubertal body growth rates on performance of Holstein heifers during first lactation.

The effects of body weight (BW) gain, different sources of protein during the prepubertal period (90 to 320 kg of BW), and the performance of Holstein heifers during their first lactation were studied. Heifers (n = 273) were assigned to one of three dietary energy treatments that were designed to achieve average daily gains of 0.6, 0.8, and 1.0 kg/d. Within each energy treatment, different protein sources (plant protein and urea or both plant and animal proteins) were imposed. Actual average daily gains by heifers on each energy treatment were 0.68, 0.83, and 0.94 kg/d for heifers that were fed diets formulated for average daily gains of 0.6, 0.8, and 1.0 kg/d, respectively, which allowed the following ages at first calving: 24.5, 22.0, and 21.3 mo. Breeding was initiated when heifers weighed approximately 340 kg. Protein sources did not affect average daily gain or milk yield. Analysis of the preplanned comparisons of actual 305-d and 4% fat-corrected milk yields indicated that yield was significantly reduced for heifers grown at 0.94 kg/d (9387 and 8558 kg, respectively) compared with that of heifers grown at 0.68 kg/d (9873 and 9008 kg, respectively). However, further regression analysis of fat-corrected milk and residual milk from a test day model on prepubertal BW gain only explained 8 and 2% of the variation in milk yield, respectively. Postcalving BW and body condition score were different among treatments. Posttreatment factors, such as postcalving BW, accounted for more of the variation in milk yield than did prepubertal BW gain. Prepubertal BW gains, when evaluated on a continuum from 0.5 to 1.1 kg/d, explained little of the variation in milk yield; therefore, BW gain during the prepubertal period did not significantly affect milk yield during first lactation.

Adipose Tissue↗

PubMed1998

Downregulation of class II antigen expression by FGF-heparin complexes is due primarily to heparin effect.

Fibroblast growth factors are thought to play a role in the pathogenesis of autoimmune inflammation. The evidence linking these growth factors to autoimmunity stems in part from their presence in mononuclear cells from inflammatory sites during disease processes. We sought to further dissect the mechanisms through which fibroblast growth factors might affect the inflammatory response. Peritoneal macrophages from autoimmune MRL 1pr/1pr mice and congenic wild-type MRL +/+ mice were cultured for 72 hours in the presence of either IFN-gamma, heparin, FGF-1, FGF-2, FGF-1 plus heparin, FGF-2 plus heparin or medium alone. Expression of MHC class II (I-Ak and I-Ek) antigens were analyzed using direct immunofluorescence and flow cytometry. As expected, at baseline there were higher numbers of I-Ak bearing cells in elicited peritoneal cells from 1pr mice relative to +/+ cells (70.8 +/- 14.9 versus 43.4 +/- 19.7, p = 0.046). Expression of I-Ak and I-Ek and percentage of I-E bearing cells were essentially the same between strains. Cells from 1pr and +/+ mice displayed reductions in the percentage of I-Ak expressing cells following culture with FGF-1 plus heparin and FGF-2 plus heparin. Similarly, cells from both 1pr and +/+ mice displayed significant reductions from baseline I-Ak expression following culture with FGF-1 and FGF-2 in the presence of heparin. Similar reductions were seen in cells from both strains cultured with heparin alone. No change from baseline was discernible when cells were cultured in the presence of FGF-1 or FGF-2 alone. Titration studies showed a maximum heparin effect at 5 units/ml culture. However, reduced amounts of heparin in the cell culture were directly proportional to decreased levels of I-Ak expression. These results suggest that cells from autoimmune MRL 1pr/1pr mice and wild type MRL +/+ mice respond similarly with a general reduction of I-Ak expression and a decrease in the percentage of I-Ak bearing cells in response to heparin with little discernible effect from addition of either FGF-1 or FGF-2. This change in class II expression suggests that the heparin-heparan component in FGF-heparin complexes may serve to downregulate class II expression during inflammation.

Animals↗

PubMed1995

Multiplicative factors for estimation of daily milk and component yields from single morning or afternoon tests.

Prediction of daily yield from single a.m. or p.m. milkings requires factors that are the reciprocal of the proportion of total yield expected from single milkings given the milking interval. Further adjustments to estimated milk yield account for DIM. Factors used by the Cornell Dairy Records Processing Lab were estimated from data collected from August 1983 to November 1984. These factors appear to be biased. Inconsistent estimates of daily yield were observed monthly. New factors were developed using recent data. Factors from a.m. milkings for milk and protein yield were smaller than those currently in use. The reverse was true for fat yield. Covariants for DIM were larger than those currently used. Differences were observed when factors using data with known and assumed milking intervals were compared. Factors for a.m. milkings with known intervals were smaller than those from p.m. milkings with the same known intervals. Use of covariants for DIM were compared with covariants for single milk yield. The latter explained more variation in yield. Factors were tested on independent data. New factors with covariants for single milk yield performed best for estimation of total daily yield.

Animals↗

PubMed1993

Genetic parameters of Italian brown Swiss for levels of herd yield.

Genetic parameters were estimated for yields and percentages of milk, fat, and protein for registered Italian Brown Swiss cows. Data were 72,690 mature equivalent 305-d first lactation yields split by herd average milk into four files. An expectation-maximization REML algorithm was used on a multiple-trait model with equal design matrices for fixed and random effects. Data were preadjusted for geographical area, age-month of calving, and days open. The model included herd-year and sire genetic group as fixed effects and sires as random effects. Estimates of heritability were .28, .30, .26, .42, and .34 for milk, fat, and protein yields, and fat and protein percentages, respectively. Genetic correlations of milk yield and milk component percentages were negative, as expected. Correlation of protein yield and protein percentage was null. Results show an increasing tend of variance components from low to high herd yields, indicating that dispersion of yield about the mean increases as average yield increases. Relative differences among environmental components were larger than those among genetic components, yielding larger estimates of heritability in herds with lower yield. Estimates of heritability for milk from low to high herd yields were .42, .38, .35, and .33.

Animals↗

PubMed1992

Estimating milk, fat, and protein lactation curves with a test day model.

Test day models were used to estimate lactation curves for milk, fat, protein, fat percentage, and protein percentage and to study the influence of age, season, and herd productivity on Holstein lactation curves. Random effects of lactation within herd and fixed effects of herd test date were absorbed. Fixed effects of cow's age on test day and either DIM (57 divisions) by parity (1, 2, greater than or equal to 3) class or season of calving (winter or summer) by DIM by parity class were estimated. Lactation curves for yield traits derived from DIM solutions were flatter for first versus later lactation, even without addition of age effects. Differences between lactation curves for the two seasons were slight, suggesting that most observed seasonal differences are caused by seasonal productivity accounted for by herd test date effects. At peak, winter calving cows yielded slightly more milk of similar fat percentage but of lower protein percentage than those calving in summer. Data were also partitioned into nine subsets based on rolling herd milk and fat percentage. Lactation curves for yield traits, but not percentage traits, varied with rolling herd milk. Lactation curves for fat yield and percentage varied with rolling herd fat percentage.

Age Factors↗

PubMed1988

Treatment of unusual Kock pouch urinary calculi with extracorporeal shock wave lithotripsy.

Since the establishment of extracorporeal shock wave lithotripsy for the treatment of upper urinary tract calculi, further potential applications have been explored. We report the successful use of extracorporeal shock wave lithotripsy for the treatment of obstructive calculi on staples within the afferent nipple of a Kock pouch ureteroileal urinary diversion.

Adult↗

PubMed1986

Semen fertility--an evaluation system for artificial insemination sires, technicians, herds, and systematic fixed effects.

Semen fertility was evaluated on 4478 artificial insemination bulls using 2,007,520 breeding receipts for inseminations to 397,979 Holstein cows between January 1, 1978 and November 1, 1984 using mixed linear model methodology. Bulls differed on average by +/- 3.68% conception. Differences between herd-years ranged from 27.4 to -32.3% conception with an average difference of +/- 8.33%. Within herds, cow parity-service number accounted for the largest variation, ranging from 24.0% to -18.5% conception. June was the best month for conception (1.9) and January the poorest (-2.3), indicating effect of temperature and confinement in winter on estrous detection in the northeastern United States. Cows with intervals between repeat services of 21 d had conception rates 12% higher than intervals between repeat services of 11 d. Effect of month-year of semen collection varied by +/- 1.33% conception. Differences between technicians within years varied by +/- 3.37%. Results of the analysis indicate improved conception on dairy farms can be achieved by improved estrous detection, which is a major component of herd-year and service interval. Other components of the model contributed little to the variance in conception or are uncontrollable by farm management.

Animals↗

PubMed1986

Effect of days carried calf, days dry, and weight of first calf heifers on yield.

Effects of days carried calf, days dry, and weight of first calf heifers were studied using records of Holstein cows processed at the Northeast Dairy Records Processing Laboratory between July 1980 and August 1984. Multiplicative factors were estimated for days carried calf for milk, fat, and protein using a model that adjusted for the age-month and herd-year of freshening. Factors developed show a close relationship between protein and milk with fat factors being smaller. Factors also are smaller than others reported in the literature. First lactation factors differed from second and third lactation factors. Analysis of days dry indicated that optimum number of days dry between lactations 1 and 2, 2 and 3, and 3 and 4 for maximized subsequent yield was 51 to 60 d dry for all lactations. Calculated F values showed greater significance for days dry than age-month of freshening. Optimum freshening weight of a first calf heifer to maximize first lactation milk yield is between 544 and 567 kg. The F values for weight at freshening were more significant than age-month of freshening.

Animals↗

PubMed1985

Systematic environmental, direct, and service sire effects on conception rate in artificially inseminated Holstein cows.

Result of insemination was verified for 329,314 artificial inseminations by 882 service sires to 97,245 Holstein cows in 1,075 herds between May 1970 and December 1983. Estimates of systematic environmental and genetic components of cow and service sire components of conception rate were obtained preliminary to development of a fertility monitoring system. Conception rate was 2.9% higher in stanchion than loose housed herds and 2.3% higher in grade than registered cows. Fall months were superior to winter months, the greatest difference being 6.1% between October and January. Conception rate increased with herd milk production, decreased with both increased cow age, and increased herd size in mature and old cows. Regions and inseminators within regions were highly variable. Conception may be influenced by semen price; however, week day of insemination and duration of semen storage had no effect. Conception rate decreased for semen by bulls 8 yr and older, was lowest for semen harvested in June, but no season of collection effect was detected. No genetic trends for cow and service sire conception rate were found; heritability and repeatability were .08 and .06, respectively. Genetic correlations between cow and service sire conception rate and these components with first lactation production and semen output measures were all near zero. Therefore, the relationship between sire fertility and daughter fertility is near zero.

Animals↗

PubMed1984

Phenotypic and genetic statistics of components of milk and two measures of somatic cell concentration.

Heritabilities, genotypic and phenotypic correlations for milk, fat, and protein yields, and two traits related to somatic cell concentration (cumulative lactation score and lactational somatic cell concentration) were estimated. A total of 18,416 first lactations of Holstein cows were analyzed by a new procedure for estimating variance components. Heritabilities were .21, .23, .19, .17, and .61 for milk, fat, and protein yields, cumulative lactation score, and lactational somatic cell concentration. Addition of protein yields to the current selection for two traits with nil economic value for protein would improve genetic gains for fat and milk yields in the northeastern United States. If cumulative lactation score and lactational somatic cell concentration were incorporated in current selection for two traits, restricted selection indexes should be used to avoid reduction in genetic gains for milk and fat yields.

Animals↗

PubMed1984

Impact of genetic manipulation.

Genetic progress for production in dairy cattle is 50% or less of optimum. Manipulation of the reproductive process to increase genetic gains was reviewed. Economics of manipulating the reproductive process was evaluated by equating future discounted net income to current discounted expenses and solving for the break-even cost of the technique for 1 to n years the technique is employed. Techniques such as embryo transfer and sexed semen can be evaluated for economics. A system of splitting female embryos to produce performance-tested female genotypes was presented. The system has the capability of increasing genetic gains per year by 35%. The proposed system could be profitable if it is incorporated in the artificial insemination system and directed by professional geneticists.

Animals↗

PubMed1983

Comparison of teat dips with differing iodine concentrations in prevention of mastitis infection.

Six commercial dairy herds were used to test the relative efficacy of three concentrations of iodine as a teat dip over 12 mo. Concentrations were .1, .25, and 1% iodine with free iodine contents of 3.5, 4.0, and 1.0 ppm. Two concentrations were compared in each herd. The greatest number of new infections (71) occurred in approximately 120 cows whose teats were dipped with the 1% iodine dip, and the fewest (52) occurred in a similar number of cow quarters dipped in .1% iodine; however, differences were not significant. Clinical mastitis was highest in the 1% group. If all clinical mastitis were the result of infection, even if bacteria were not isolated from the pretreatment sample or from samples collected at the start of the study and those quarters were added to the totals, then reduction of new infection with the .1% product would be significant.

Administration, Topical↗

PubMed1982

Effect of overmilking on udder health.

This study evaluated the effect on udder health of extending the milking period with or without vacuum fluctuation. Eighty cows were allotted into treatment groups consisting of 1) Control milked with normal milking equipment and the milker removed as soon as milk flow ceases; 2) milked for 12 min with normal equipment; 3) milked 12 min with induced vacuum fluctuations; and 4) normal milking time with induced fluctuations. Groups 2 and 3 had more newly infected quarters than groups 1 and 4. However, there was no difference in the number of cows becoming infected. The increase in new infections is due to more quarters of already infected cows becoming infected rather than more new cows becoming infected. Extending the machine-on time appeared to increase the rate of cross infection presumably by lengthening the time of highest risk. Cows in groups 2 and 3 required more therapy of clinical mastitis which was a reflection of the higher new infection rate rather than of a change in trauma to the udder. Increasing the unit-on time had no apparent effect on external teat end condition.

Animals↗

PubMed1982

Environmental influences on semen output.

Semen output characteristics of 7,858 ejaculates of 57 commercial Holstein sires in artificial insemination were analyzed to estimate effects of environment over 3-yr. Large differences existed between bulls, first and second ejaculates, and intervals between collections for all measures of semen output. Effects of age of bulls were greatest for sperm concentration per milliliter and total sperm output, peaking at 4 yr of age. Original semen volume was influenced less by age. December was the best month for total sperm production even though June and July were the months for most volume of seminal fluid production. Total sperm output was highest on Fridays and lowest on Wednesdays. Effects of temperature and humidity and changes in temperature and humidity on semen output were small and inconsistent. These results do not support the assumption that semen output could be increased in controlled environment conditions.

Age Factors↗

PubMed1982

Effect of Dursban 44 on semen output of Holstein bulls.

Dursban 44, an insecticide for lice control, was applied to 185 Holstein bulls 9 to 52 mo of age. These sires were in various stages of progeny testing at an artificial insemination center. Application of this product killed 7 bulls, and the remaining bulls exhibited varying severity of illness with 6 classified as very sick. This study evaluated the effect of this illness on semen production. Semen output on 40,950 ejaculates from 583 Holstein bulls collected from July 1, 1975, through March 31, 1981, was analyzed to establish normal semen production and to estimate the effect of illness caused by Dursban 44 treatment. Ejaculate number, days between collections by previous number of ejaculates, calendar months, years, and ages of bulls affected the semen output characteristics, original volume, sperm concentration, percent motile sperm, total sperm per ejaculate, percent prefreeze discards, percent postthaw sperm motility, and percent postthaw discards. Ejaculate volume, motility, total percent prefreeze discards, and percent postthaw discards were influenced negatively on the 6 very sick bulls. Percent postthaw discards were higher on all bulls treated with Dursban 44 for up to 6 mo post-treatment.

Animals↗