Kg Of Milk Yield Research Articles

Genetic relationships between reproductive disorders, operational days open and milk yield

Abstract The data on 23 196 Ayrshire cows were extracted from the Finnish health register for dairy cattle to study the relationships of veterinary diagnoses of ovulatory disorder and metritis within 150 d postpartum across the first three lactations. A subset of 11 173 disease recordings was merged with information on 305 d milk yield and operational days open to study the genetic correlations between reproduction disorders, daughter fertility, and milk production. (Co)variance components were estimated using linear multitrait REML and the expectation-maximization algorithm with a sire model. The estimates of genetic correlations between different lactations were positive and from moderate to high for operational days open (0.77 to 0.93) and ovulatory disorder (0.60 to 0.94). The high genetic correlation between ovulatory disorder and operational days open (0.80) indicates that the both traits are expressions of the same trait complex. A moderately high unfavourable genetic association was found between milk yield and both reproductive disorder and operational days open. Based on the results, a genetic improvement of 500 kg in milk yield would, as a correlated response, result in an increase of 1.7 %-units, 0.9 %-units and 4.2 d in the frequency of ovulatory disorder and of metritis, and in operational days open, respectively.

Evaluation of Breeding Value and Selection of Bull Dams in the Danish Dairy Breeds: I. Studies on Realized Efficiency of Bull Dam and Bull Sire Selection

Abstract The relationship between twice the adjusted daughter yield deviation (DYD) of the son and the average of the estimated breeding values (EBV) of his parents was investigated for milk and fat yield. Deviations from expectations of DYD minus the pedigree index and the regression of DYD on the EBV for each of the parents were estimated. The EBV of each bull dam was calculated in several ways using different combinations of pedigree information and their own records. In all, 1693 bulls (880 Black and White (BW), 418 Red Danish (RD) and 395 Danish Jersey (DJ)) with Direct Updating indices for milk and fat yield were included in the investigation. Mean discrepancies between estimated and observed genetic merit for kg of milk yield were −348 for BW, −213 for RD and −228 for DJ, when all of the bull dams' individual records were utilized in breeding value estimation. The corresponding mean discrepancies for kg of fat yield were −14.7, −11.5 and −11.9, respectively. The discrepancies were positively correl...

Effects of Treatment of Dairy Cows with Recombinant Bovine Somatotropin over Three or Four Lactations

Jersey, Dutch Red and White, and Friesian cows were subcutaneously injected with 640mg of recombinant bST at 28-d intervals from 87 to 115 d after calving through four successive lactations. A TMR (6.72 MJ of NEL and 168g of CP/kg of DM) was fed for ad libitum consumption. The bST effects per day were 3.3kg for milk yield, 189g for fat yield, 109g for protein yield, 157g for lactose yield, 4 MJ of NEL for feed intake, and –4kg for body weight. Responses in blood parameters measured 7 d after injection were –.007ml for glucose, –1.3mg of N/l00ml for urea, 221 μmol/L for 3-hydroxybutyrate, 59 μmol/L for NEFA, 65 ng/L for insulin, 2.8μg/L for thyroxine, and 26.7μg/L for somatotropin. Somatic cell count in milk was 75,000 cells/ml higher in treated cows. Concentrations of NEFA, Ca, Mg, and phosphorus were unaffected. Repeatability of the maximum response in milk yield after bST treatment was low: .2 within and .5 between lactations. Cows treated in the previous lactation had slightly more retained placentas, and birth weight of their calves was 2kg less. No differences were observed between treated and control cows in disease incidence. Six treated cows were culled in third and fourth lactations. No indications for tissue damage, inflammation, or stress after bST injections were detected.

International evaluation of Holstein-Friesian dairy sires from three countries

Official 1985 genetic evaluations of Holstein-Friesian dairy sires for milk yield, fat yield and fat percentage from Canada and the U.S.A. were pooled with unofficial 1985 genetic evaluations of sires from Italy in order to obtain international evaluations of sires for these three countries. There were 1766 sires from Canada, 9746 from the U.S.A. and 4191 from Italy with at least 20 daughters or 5 effective daughters each. The linear model for describing a sire's daughter average, free of all non-genetic fixed effects, included the country of proof, the country of origin and year of birth, sires within country of origin and year of birth and all additive genetic relationships among bulls. Daughter averages were approximated by de-regressing sire proofs and accounting for year of birth within country. Differences in country of proof solutions reflect differences in genetic bases of evaluation; the Italian minus the Canadian and the U.S. solutions were, respectively, 334 and 565 kg for milk yield, 14.4 and 19.6 kg for fat yield, and 0.05 and -0.01% for fat percentage. Between 1955–1959 and 1960–1964, there was very little genetic progress in all countries. Genetic change in sires born between 1965–1969 and 1975–1979 were 121, 198 and 87 kg for milk yield, 4.6, 6.0 and 2.4 kg for fat yield, and 0.01, -0.02 and -0.02% for fat percentage in Canada, the U.S.A. and Italy, respectively. Sires imported to Canada, the U.S.A. and Italy had average evaluations different from those of local sires within countries by 126, -211 and 45 kg for milk yield, 4.2, -6.4 and 2.0 kg for fat yield, and -0.01, 0.02 and 0.01% for fat percentage, respectively. The estimation of international sire breeding values on a routine basis was shown to be feasible, but many problems still remain to be solved. Besides the need for sufficient links between countries, the primary problem is that of accounting for non-random mating of sires within each country.

Correlations Among First and Second Lactation Milk Yield and Calving Interval

Estimates of genetic correlations were .17 between first lactation milk yield and concurrent calving interval, .10 between second lactation milk yield and first calving interval, and .82 between first and second milk yields. Corresponding phenotypic correlations were .27, .16, and .58. Heritability estimates were .27 and .25 for first and second lactations and .15 for calving interval. Estimates were averages of two samples of 15 New York State herds averaging 144 Al-sired Holstein cows and 30 sires. Milk yields were 305-d, mature equivalent. Calving interval was days between first and second freshening. First milk records without a second freshening were included. Multiple-trait animal model included separate herd-year-season effects for first and second milk yields and calving interval. Numerator relationships among animals within herd, except for daughter-dam relationships, were included. The REML with the expectation-maximization algorithm was used to estimate (co)variance matrices among genetic values and environmental effects for the three traits. Results indicate a need to adjust milk records for the phenotypic effects of current and previous calving interval. The genetic association, however, between fertility and milk yield appears small. Genetic improvement of 450kg of milk yield may result in 2 added d to first calving interval.

The performance of Jersey cows and cows of larger dairy breeds on two complete diets with different roughage contents

A group of 38 Jersey cows and a control group of 12 Holstein Friesian (HF), 12 Dutch Friesian (DF) and 10 Dutch Red and White (DRW) cows were fed, after their third calving, a complete diet of roughage (R) or a complete diet of the same roughage with 50% concentrates on a dry matter basis (C). Body weight, milk production and feed intake were recorded during the first 39 weeks of lactation. All cows had already participated in this experiment in their first lactation on the same diets. For the characteristics studied, the differences between the breeds on both diets were not equal. However, only for fat percentage was a significant breed × diet interaction found. Mean differences between the Jersey and the HF + DF + DRW group for the C diet and for the R diet (in parentheses) were −936 (−748) kVEM (1 kVEM=6.9 MJ NE) for energy intake; −2560 (−1707) kg for milk yield; +2.82 (+2.38) for fat percentage; +0.83 (+0.77) for protein percentage; +3 (+23) kg for fat yield; −55 (−26) kg for protein yield; −199 (−216) kg for average body weight; −57 (−27) kg for weight gain. From first to third lactation, energy intake and milk yield for the Jerseys and the HF + DF + DRW increased in the C diet groups by 25 and 24%, respectively, and in the R diet groups by 48 and 51%, respectively. The biological efficiency for milk production (energy in milk divided by net energy in feed) was 57% for the Jersey group on the C diet, 69% for the Jersey group on the R diet, 56% for the HF + DF + DRW group on the C diet and 61% for the HF + DF + DRW group on the R diet.

The performance of Jersey heifers and heifers of larger dairy breeds on two complete diets with different roughage contents

A group of 48 Jersey heifers and a control group of 16 Holstein Friesian (HF), 16 Dutch Friesian (DF) and 16 Dutch Red and White (DRW) heifers were fed ad libitum after calving, a complete diet of roughage (R) or a complete diet of the same roughage with 50% concentrates on a dry matter basis (C). Body weight, milk production and feed intake were recorded in the first 39 weeks of lactation. For feed intake, milk yield, fat percentage and protein yield a significant breed × diet interaction was found, which was caused by non-equal differences between the breeds on the different diets. Mean differences between the Jersey and the HF + DF + DRW group for the C diet were: −946 kVEM for energy intake; −1791 kg for milk yield; 2.31 for fat percentage; 0.72 for protein percentage; −5 kg for fat yield; and −39 kg for protein yield. The mean differences for the R diet were: −626 kVEM for energy intake; −991 kg for milk yield; 1.84 for fat percentage; 0.56 for protein percentage; 7 kg for fat yield; and −16 kg for protein yield. Between the Jersey and the HF + DF + DRW group the mean difference in body weight was −164 kg during the trial, and the HF + DF + DRW group had a 38 kg higher body weight gain than the Jersey group. The biological efficiency for milk production (energy in milk divided by net energy in feed) was 59% for the Jersey group on the C diet, 65% for the Jersey group on the R diet, 55% for the HF + DF + DRW group on the C diet and 56% for the HF + DF + DRW group on the R diet.

Increasing Pedigree Contribution to Dairy Sire Evaluation

Methods to improve contributions of ancestor information to sire evaluations computed by the Modified Contemporary Comparison were studied. Pedigree index (one-half evaluation of sire plus one-fourth evaluation of maternal grandsire) was used to indicate ancestor merit with adjustment for type of sampling program and birth date. For Holsteins, effect of sampling through artificial insemination was 35kg for milk yield; effect of birth date (trend of daughter merit not accounted for by pedigree index or type of sampling) was 7.3kg/yr for milk yield and .36kg/yr for fat yield. Trends were larger for milk and fat yields of Ayrshires, Brown Swiss, Guernseys, and Jerseys except for fat yield of Ayrshires, which had no significant trend. Correlations of daughter merit with pedigree index and with present group average (average daughter merit of bulls with similar pedigree indexes for milk yield) were computed. For milk yield, correlations of daughter merit with pedigree index and with group average were nearly the same; however, for fat yield, pedigree index had a higher correlation with daughter merit than did group average. Accounting for residual trend resulted in further increase of correlation. Replacing one-fourth evaluation of maternal grandsire with one-half Cow Index of dam also improved correlations slightly. Evaluations can be modified so that pedigree index adjusted by birth date replaces group average in representing ancestor merit. Such evaluations better predict performance of future daughters than do evaluations with grouping by pedigree index for milk yield, particularly for evaluations for fat yield. Dam's Cow Index provides little additional information.

SUPPLEMENTATION WITH PROTECTED LIPID AS A MEANS OF ALLEVIATING "SPRING PASTURE" INDUCED MILK FAT DEPRESSION

Thirty-six lactating cows, after their first week on spring pasture, were subdivided into three groups of 12 cows each and assigned to one of three pelleted grain mixtures containing 0, 5 or 10% protected lipid. These grain mixtures were fed in the milking parlor at the rate of 1.0 kg/4.0 kg of milk yield for a period of 14 days and then the cows were switched to the next ration in the sequence. Milk yield and grain intake were recorded daily. Milk samples for fat, protein and lactose determinations were taken during the last week of the drylot feeding period, during the preliminary pasture period and on the last 2 days of each experimental period. The change in feeding system from drylot to pasture resulted in an average decrease of 0.65 and 0.10 percentage units in milk fat and lactose contents, respectively, and an increase of 0.27 of a percentage unit in protein content. Refusals of the grain mixture were greater (P < 0.05) but milk yields per kilogram of grain intake were higher (P < 0.05) for grain mixtures containing 10% protected lipid than for the control ration. Protected lipid was not effective in countering the milk fat depression caused by the onset of the spring grazing season. The feeding of protected lipid at the rate of 5 and 10% resulted in only a 10 and 27% recovery in total fat yield compared to cows fed the control ration.

Sire Comparison for Holsteins in Mexico Versus the United States and Canada

Henderson's mixed model procedure was used to determine sire comparisons for Holstein sires from the United States, Canada, or local bred in 48 Mexican herds. For sires with five or more daughters, 74% of the sires in artificial insemination from the United States had plus values compared to 34% from Canada, 44% from the local stud, and 40% for local bred sires. Genetic correlations with Mexican sire comparisons were Northeast Artificial Insemination Sire Comparison with >20 daughters in Mexico .86, with 10 to 20 daughters .71, United States Department of Agriculture (USDA) proof >10 daughters .81, and Canada Northeast Artificial Insemination Sire Comparison with >10 daughters .61. Correlations with United States proofs indicate effects of sire by location were small. Cow origins were imports from Canada or the United States (imports), sired by imported semen or sires (.5 imports), and locally bred (locals). Differences between imports and .5 imports were small, but cows of United States origin exceeded Canadian by 300 to 500kg in milk yield. Progeny of imported sires (.5 imports) were lower in milk yield than progeny from sires in artificial insemination. Locally produced cattle were poorer than imports or .5 imports by sires in the United States or Canada.

EFFECTS OF AD LIBITUM VERSUS RESTRICTED INTAKE OF CONCENTRATE AND STAGE OF LACTATION ON THE MINERAL CONTENT OF COW’S MILK

Concentrates, one consisting primarily of oats and the other barley, were fed ad libitum to cows or at the rate of 1 kg per 3 kg of milk yield for an entire lactation. Calcium, potassium, magnesium and sodium content of the milk and milk yield were measured monthly. Potassium content and milk yield decreased and sodium content increased significantly (P < 0.05) with advancing stage of lactation. The calcium content of milk was significantly greater (P < 0.05) when the barley-based compared with the oat-based concentrate was fed. The sodium content of milk from cows fed concentrate ad libitum was significantly higher than from cows fed restricted amounts of concentrate. Ayrshire milk was significantly greater (P < 0.05) in magnesium concentration than Holstein milk.

Variations in the Time Required to Milk Cows

Time required to milk and rate of milk flow are largely characteristics of individual cows, as differences among cows of the same breed account for 55.7 and 52.2% of the total variances of the two traits, respectively. An average of 5.19 minutes elapsed from attaching the last teat cup until all teat cups were removed; 2.18kg of milk was removed in the first minute and 4.36kg in the first two minutes, while the average for the maximum amount of milk removed in one minute was 2.59kg. Maximum rate increased .202±.024kg and time increased .270±.035 minutes for each increase of 1kg in milk yield per milking. Time required to milk can be predicted from the first powers of yield of milk per milking and measures of rate of flow with a high degree of accuracy; the multiple correlations ranged from 0.86 to 0.90. Maximum rate of flow, yield in the first two minutes are all adequate measures of rate of flow. Milking time increased 0.51 minute for each increase of one kilogram in yield of milk per milking independent of maximum rate and decreased 1.22 minutes for each increase of one kilogram in maximum rate of flow independent of yield per milking.