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G L Hargrove

Publications and source records attributed to G L Hargrove.

15 recordsLinked to original sources
PubMed2003

Heritability of intramammary infections at first parturition and relationships with sire transmitting abilities for somatic cell score, udder type traits, productive life, and protein yield.

The objective of this study was to determine the relationships among daughter intramammary infections at first parturition and sire transmitting abilities for somatic cell score, udder type traits, productive life, and protein yield. Quarter milk samples from 958 daughters (in eight Pennsylvania herds and one Nebraska herd) of 182 Holstein sires were collected within a few days of first calving and cultured to determine intramammary infection status. A total of 446 cows had intramammary infections in 835 quarters at first parturition. Incidence of intramammary infections at first parturition and the proportion of quarters infected per cow were regressed on age at first calving, days in milk at sample collection, herd-season of calving (a classification variable), and sire transmitting abilities taken one at a time. Linear effects, non-linear effects, and odds ratios were estimated for sire transmitting abilities. Separate, preplanned analyses were conducted on data from one herd that gave all heifers an intramammary antibiotic infusion in each quarter 30 d prior to the expected calving date. Separate analyses were also conducted on dependent variables that considered intramammary infections at first parturition from: all organisms, coagulase-negative staphylococci, coliform species, streptococci other than Streptococcus agalactiae, and the most common environmental organisms (coliform species and streptococci other than Streptococcus agalactiae). Daughters of sires that transmit the lowest somatic cell score had the fewest intramammary infections at first parturition. Daughters of sires that transmit longer productive life, shorter teats, and closely spaced front teats had fewer intramammary infections at first parturition. Selection for lower somatic cell score, longer productive life, shorter teats, or closely spaced front teats may reduce the incidence of intramammary infections at first parturition.

Age Factors↗
PubMed2002

Relationships among severity and duration of clinical mastitis and sire transmitting abilities for somatic cell score, udder type traits, productive life, and protein yield.

The objective of this study was to determine the relationships among severity and duration of clinical mastitis during first and second lactation and sire transmitting abilities for somatic cell score, udder type traits, productive life, and protein yield. Recording of clinical episodes began at first parturition for 1704 Holstein cows (in six Pennsylvania herds and one Nebraska herd) and continued into second lactation for 1055 of these cows. A total of 456 cows (sired by 168 bulls) had at least one clinical episode during first lactation, and 230 cows (sired by 100 bulls) had at least one clinical episode during second lactation. A severity code from 1 (normal milk) to 5 (acute systemic mastitis) was assigned daily (for up to 30 d after detection) to all quarters that had clinical mastitis. Only the severity codes for the first clinical episode to occur during first and second lactation are considered here. The initial and maximum severity codes, as well as the natural logarithms of both the sum of severity codes that were above normal (> 1) and the total days severity codes were above normal were regressed on herd (a classification variable), age at first calving, days in milk at clinical detection, and sire transmitting abilities taken one at a time. Linear and nonlinear effects were estimated for sire transmitting abilities. Separate analyses were conducted on dependent variables that considered severity and duration of clinical mastitis from: all organisms, coagulase-negative staphylococci, coliform species, streptococci other than Streptococcus agalactiae, and the most common environmental organisms (coliform species and streptococci other than Streptococcus agalactiae). Daughters of sires that transmit the lowest somatic cell score had the least severe and shortest clinical episodes from environmental organisms during first lactation. Selection for lower somatic cell score may reduce the severity and duration of clinical episodes from environmental organisms during first lactation.

Animals↗
PubMed2000

Heritability of clinical mastitis incidence and relationships with sire transmitting abilities for somatic cell score, udder type traits, productive life, and protein yield.

The objective of this study was to determine the relationships among daughter clinical mastitis during first and second lactations and sire transmitting abilities for somatic cell score, udder type traits, productive life, and protein yield. Data on clinical mastitis during first lactation were available for 1795 daughters (in six Pennsylvania herds, one Minnesota herd, and one Nebraska herd) of 283 Holstein sires. Data on clinical mastitis during second lactation were available for 1055 of these daughters. A total of 479 cows had 864 clinical episodes during first lactation, and 230 cows had 384 clinical episodes during second lactation. Clinical mastitis incidence and the total number of clinical episodes during each lactation were regressed on herd-season of calving (a classification variable), age at first calving, lactation length, and sire transmitting abilities taken one at a time. Linear effects, nonlinear effects, and odds ratios were estimated for sire transmitting abilities. Separate analyses were conducted on dependent variables that considered clinical mastitis from: all organisms, coagulase-negative staphylococci, coliform species, streptococci other than Streptococcus agalactiae, and the most common environmental organisms (coliform species and streptococci other than Streptococcus agalactiae). Heritability of clinical mastitis ranged from 0.01 to 0.42. Daughters of sires that transmit the lowest somatic cell score had the lowest incidence of clinical mastitis and the fewest clinical episodes during first and second lactations. Daughters of sires that transmit longer productive life, shallower udders, deeper udder cleft, and strongly attached fore udders had either fewer clinical episodes or lower clinical mastitis incidence during first and second lactations. The incidence of clinical mastitis and the number of clinical episodes per lactation may be reduced by selection for lower somatic cell score, longer productive life, shallower udders, deeper udder cleft, or strongly attached fore udders.

Animals↗
PubMed1995

Correlations among somatic cell scores of milk within and across lactations and linear type traits of Jerseys.

Genetic and phenotypic correlations were estimated for means of log2 SCC (somatic cell scores) from the first 305 d, the first 75 d, the first 150 d, 76 to 305 d, and 151 to 305 d of lactation for first and second lactations using REML. Somatic cell scores from the Dairy Records Processing Center in Raleigh, North Carolina for 31,180 Jersey cows sired by 411 bulls were used for analyses. Correlations between sire evaluations for somatic cell scores from this study and linear type traits from the American Jersey Cattle Club were also calculated. The model used for analyses of the somatic cell score means included herd-year of calving, age at first calving, sire, and residual. Heritability estimates for the means ranged from .05 to .15 (.12 for 305-d mean for first lactation). Genetic correlations among the somatic cell score means within first and within second lactation were > or = .79. The genetic correlation between the 305-d mean from first and second lactation was .90. The smallest genetic correlation across lactations was .68. Somatic cell scores measured at various times were under similar genetic control. Phenotypic correlations were usually much smaller than genetic correlations.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Standards of weight and height for Ayrshire, brown Swiss, and milking shorthorn heifers.

To develop a modern appraisal of growth for Ayrshire, Brown Swiss, and Milking Shorthorn dairy heifers, data on heart girth and height at withers were collected from 1279 Ayrshire heifers (33 herds), 1819 Brown Swiss heifers (46 herds), and 565 Milking Shorthorn heifers (20 herds), ages 1 to 25 mo, in herds located throughout the US. Means and standard deviations were determined for height and heart girth for each month of age. Third-order regressions on age were fitted to the means to describe height and heart girth. Estimated mean height and heart girth at 6, 12, 18, and 24 mo, in centimeters, were for Ayrshire 98.7 and 118.4, 114.4 and 145.9, 122.8 and 163.2, and 127.6 and 176.4; for Brown Swiss 102.6 and 122.3, 199.4 and 151.3, 128.7 and 168.8, and 134.0 and 182.0; and for milking Shorthorn 98.0 and 119.4, 113.6 and 148.6, 122.6 and 166.6, and 127.7 and 179.9, respectively. These data can be useful to evaluate the heifer rearing program with respect to the growth rates of heifers on an individual farm.

Aging↗
PubMed1994

Bias in composite milk samples with unequal milking intervals.

Milk samples from a herd with milk intervals approximately 14-h nights and 10-h days were used to examine potential bias in measurements with composite samples. Six consecutive milkings were weighted and sampled individually. Composite samples for a day were determined mathematically from the data. Composite samples with equal amounts from a.m. and p.m. milkings gave fat percentage measurements that were .07% above the true daily measurement. Using the milking interval to determine the portion of sample from each milking reduced this bias to -.02%. Protein percentage and SCC were satisfactory with equal sampling (mean bias of .01% and 7, respectively) but were improved slightly with milking interval sampling regimen (mean bias of .00% and 1, respectively). Fat yields were determined with equal portions, milking interval portions, and two plans available from DHIA, namely, alternate component sampling and alternate a.m.-p.m. Based on mean deviation from true fat yield, alternate a.m.-p.m. was as accurate as alternate component sampling, but variations were greater with alternate a.m.-p.m.

Animals↗
PubMed1993

Absence of quadratic relationships between genetic evaluations for somatic cell scores and udder linear traits.

Sire genetic evaluations for lactation average somatic cell scores from first and second lactation daughters were regressed in separate models on genetic evaluations for udder linear traits. Somatic cell scores were from Pennsylvania DHIA, and udder linear scores were from the Holstein Association of America classifications of first lactation cows in the northeastern US excluding Pennsylvania. The independent data files for calculation of genetic evaluations included 108,632 cows from 301 sires with udder linear scores and 58,235 cows from the same 301 sires with somatic cell scores. Sire genetic evaluations for higher udders, stronger fore udder attachments, closer teat placement, and shorter teats were associated with lower somatic cell scores. Quadratic relationships between genetic evaluations for the udder traits and somatic cell scores were not important. Quadratic components were significant only for somatic cell scores and teat length. Evaluations for intermediate teat length tended to be associated with higher somatic cell score evaluations. Selection and mating for intermediate udder depth, fore udder attachment, and front teat placement scores are not as effective in reducing somatic cell scores as selection for higher udders, stronger fore udders, and closer front teats.

Animals↗
PubMed1991

Correlations among linear type traits and somatic cell counts.

Genetic and phenotypic correlations between linear type traits and SCC were estimated from lactation average SCC from Pennsylvania DHIA and Holstein linear type evaluations from Sire Power, Inc. and Holstein Association using REML. Correlations were estimated between linear type traits and SCC measured in first lactation and between linear type traits measured in first lactation and SCC measured in second or third lactation. Data sets ranged in size from 4294 daughters of 216 sires to 58,235 daughters of 301 sires. Phenotypic and genetic correlations between the linear traits that reflect body and locomotive characteristics and SCC were generally small and unimportant. Phenotypic correlations between udder traits and SCC were variable, but cows with higher udder depth scores (higher udders) had lower SCC. Genetic correlations between udder traits and SCC were also variable. Genetic correlations between SCC and udder depth, SCC and fore udder attachment, and SCC and teat placement were negative (favorable). Genetic correlations between teat length and SCC tended to be positive. Genetic correlations were largest in magnitude between udder depth and SCC and ranged from -.21 to -.64 (weighted mean = -.35). Selection for higher udders and closer teat placement will likely improve resistance to mastitis in dairy cattle.

Animals↗
PubMed1987

Standards of weight and height for Holstein heifers.

To develop a modern appraisal of growth of Holstein dairy heifers, height at withers and heart girth (body weight) data were collected for 5723 heifers representing 163 commercial Holstein dairy herds from October 1983 through May 1985. Quadratic regression equations of height and weight on age were computed for each herd. Estimated weight and height of heifers at 24 mo from these equations were found to be correlated with herd variables such as herd average milk production and age at first calving. Means and standard deviations for height and weight were determined for each age (1 through 24 mo). Third order regressions on age were fitted to the means to describe height and weight. Estimated height (cm) and weight (kg) at 6, 12, 18, and 24 mo were 101.0, 167.2; 117.6, 299.1; 127.4, 420.6; and 132.7, 516.2. A subset of data containing heifers in 89 herds that had a herd average milk production of greater than 7264 kg were also fitted to third order regression on age. Weight and height of dairy heifers are moderately larger in herds with greater than 7264 kg average milk production. Based on the entire data set, commercial Holstein herds in Pennsylvania have heifers somewhat larger than those used to develop National Research Council recommendations.

Aging↗
PubMed1985

Effect of automatic backflushing on number of new intramammary infections, bacteria on teatcup liners, and milk iodine.

Effect of an automatic iodine (15 ppm) backflushing system on incidence of new intramammary infections, teatcup liner bacterial populations, and milk iodine was tested in a herd free of Streptococcus agalactiae and with a low prevalence of Staphylococcus aureus. In an 11-mo trial, backflushing was applied to teatcups that milked the right half of the udder; the left half served as control. Clawpieces were divided into left and right halves with each having a milk outlet. Postmilking teat dipping was discontinued. All lactating cows in the University herd were used, averaging 154 with normal attrition and additions of new individuals as they calved. Backflushing reduced numbers of staphylococci recovered from liners by 98.5% and Gram-negative bacteria by 99.5% as compared with unflushed liners. Backflushing significantly reduced new infections caused by Corynebacterium bovis. However, there was no effect on incidence of new infections by staphylococci, streptococci, or coliforms. Iodine concentrations averaged 243 micrograms per liter in milk from control quarters and 486 micrograms from backflushed udder halves. Interior surface cracking was more severe in backflushed teatcup liners than in control liners. These results do not justify the use of backflushing in a herd with low prevalence of contagious pathogens.

Animals↗
PubMed1984

Differences in morning and evening sample milkings and adjustment to daily weights and percents.

Dairy Herd Improvement Association sample-day data were analyzed 1) to explain variation of month-to-month differences of single milking yields and fat percents and 2) to develop adjustment factors for estimating daily yield and fat tests from a single milking. Prior to analyses, single sample data were adjusted for month-to-month differences determined from standard two sample data. Guernsey and Holstein data involving 1,632 and 16,784 cows were available in the single sample files. Analyses were separate for Guernseys and Holsteins and for yield and test. Regression equations involving from 13 to 16 independent variables accounted for proportions of variance of the dependent variable ranging from .31 to .48 for the four combinations of breed and trait. Regression equations for adjustment of Dairy Herd Improvement Association single sample data were developed. Each equation included only two independent variables for adjustment purposes. Those equations developed from Holstein data have been implemented by the Pennsylvania Dairy Herd Improvement Association to adjust single sample data for all breeds.

Animals↗
PubMed1983

Performance of dairy cows in midlactation fed high quality grass pasture and concentrate at three percents of energy requirements.

Thirty multiparous cows rotationally grazed high quality grass pastures (predominantly Dactylis glomerata and Poa pratensis) for 140 days. Stage of lactation was 54 to 192 days at beginning of trial. Cows were offered concentrates to supply 33, 66, or 100% of requirements for net energy for lactation above maintenance; daily intakes by the three groups averaged 3.5, 7.7, and 11.5 kg. Refusal of concentrate tended to increase with supplementation. Average milk production was 19.2, 20.4, and 21.5 kg. When individual yields were compared with an initial 2-wk period prior to trial, there was no difference in decline in milk flow, except for one 28-day period in midsummer when decline by the 33% group was greater than that by the 100% group. Milk fat yields were similar. Milk protein yields by the 100% group were significantly higher than those by the 33% group. Body weight changes were similar among groups. Quality of forage was high, and yields were adequate. Changes in milk flow attributable to movement of cows to fresh pastures were +1.35 kg per cow daily. Variations in in vitro dry matter disappearance, crude protein, and dry matter of forage were positively associated with changes in milk flow.

Animals↗
PubMed1981

Genetic and environmental influences on milk and milk component production.

Estimates of genetic parameters and environmental correlations were from deviations from modified contemporary average of standardized records of first lactations of Holsteins in Pennsylvania. Records were extended to 305 days and adjusted for month of calving prior to calculation of deviations. Heritabilities from intrasire correlations among paternal sisters were .23, .26, .22, .71, and .64 for yields of milk, fat, and protein, and percentages of fat and protein. Genetic correlations were positive and generally high between yields and between percentages. Correlations of milk yield with percentages were strongly negative. Environmental correlations among paternal sisters in the same herd were .08, .11, .10, -.04, and -.03 for yields of milk, fat, and protein, and percentages of fat and protein. These statistics will be useful to plan optimum selection programs and to improve sire evaluation procedures, particularly for protein content and yield.

Animals↗
PubMed1980

Genetic polymorphisms of blood and milk and reproduction in Holstein cattle.

Associations of blood and milk protein polymorphisms with reproductive performance were examined in more than 32,000 services in 15,000 service periods of 6,000 cows and 700 service sires in Holsteins. Seven blood groups, one serum protein, and four milk proteins were analyzed for relation to reproductive traits including conception rate and days open. Associations between polymorphic systems and reproductive traits in 15 of 112 analyses were significant. The S blood system appeared most influential, having statistical significance in five of ten traits. These were conception rates in all services for female phenotypes, male phenotypes, and male by female phenotypes combined, conception rate in first services for female phenotypes, and probability of conception for female phenotypes. The FV system influenced conception rates in all services and in first services for male by female phenotypes combined. Four of the polymorphic systems had no effect on any of the reproductive traits. Maternal-fetal incompatibility was not evident from comparing parental combinations of aborted fetuses and normal calves. Conception rates declined with age of cow. For animals that ultimately conceived, conception rates did not decline consistently from first to later services within a service period.

Animals↗