Butterfat Production Research Articles

THE HERITABILITY OF VARIOUS TYPE COMPONENTS AND THEIR RELATIONSHIP TO PRODUCTION IN CANADIAN JERSEY CATTLE

The official type records of Canadian Jersey cows classified from 1946 to 1954 (inclusive) were analysed to determine the heritability of final or over-all type rating and ten of its components as listed on the Canadian Jersey Cattle Club type breakdown form. Records of all classified cows with official Record of Performance production were analysed to determine the relationship between type rating and production in the lactation nearest to date of classification.The results of this study indicate that the within sire, within herd, heritabilities of type characteristics in Canadian Jerseys are relatively low ranging from.07 for "rear udder" to.30 for "legs, pasterns and feet with over-all type having a heritability of.24. There is a small, positive phenotypic correlation between type and milk production and between type and butterfat production in the Jersey breed in Canada. The correlations range from.08 to.23 between various type components and production with over-all type having a correlation of.16 to milk production and.20 to butterfat production. There is no significant correlation between type and butterfat test in this population of dairy cows.

Heritability and Repeatability of First, Second, Third, and Fourth Records of Varying Duration in Brown Swiss Cattle1,2,3

Summary Heritability estimates of first, second, third, and fourth lactations, averages of two, three, and four records, and of 100- and 200-day partial first lactations, were made to study the reliability of using partial or complete first records as the basis for early selection in Brown Swiss cattle. The data consisted of 8,413 HIR records of not less than 200 or more than 305 days in length from 38 Brown Swiss herds in Wisconsin. Heritability estimates, obtained by doubling the intrasire regression of daughters on dams, were 0.42 for milk, 0.37 for butterfat, and 0.80 for percentage of butterfat for the first lactation. Estimates for milk and butterfat production, using partial first records, were of the order of 0.30 and 0.34 for 100- and 200-day yields, respectively. For percentage of butterfat, the values were 0.44 and 0.63, respectively. Repeatability values were 0.47 for milk, 0.45 for butterfat, and 0.68 for percentage of butterfat. Herds, sires, and cows in sire accounted for 25, 14, and 21%, respectively, of the total variance in milk yield. In selecting for production traits in Brown Swiss cattle, first records appear to be as valuable as any other single record or average of records. Partial first records of 100 or 200 days in length will be almost as effective in improving milk and fat yield as selection based on 305-day first records. The heritability estimates found in this study of Brown Swiss cattle are slightly higher than those previously reported for production traits in other breeds of dairy cattle in the United States. However, most of the previously reported estimates fall within the lower range of the fiducial limits reported here.

Some Effects of Certain Environmental and Inherited Influences upon Milk and Fat Production in Dairy Cattle1,2

Summary The IBM-DHIA records of 2,364 cows of four breeds were analyzed to study the effects of breed, season of calving, gestation, preceding dry period, and body weight upon milk, FCM, and butterfat production in southeastern United States. The total regressions for milk, FCM, and fat were highly significant due to the combined effects of the five variables with R 2 values of 40.5, 31.0, and 24.9%, respectively. Partial regressions of FCM and fat yield on season of calving, gestation, and body weight were significant. The effect of the length of preceding dry period in this study was negligible. Breed differences accounted for 11% of the variation in milk production, 7.4% of the variation in FCM production, but only 3.7% of the variation in fat yield.

Interrelationships Between Certain Measurements of External Body Form, Internal Anatomy, and Fat Production

Summary Correlations between butterfat production and certain measurements of external body form were calculated from data on 216 first-lactation Holstein cows in the Beltsville herd. The correlations between production and cross-section areas of chest or paunch were lower, in most cases, than those between production and other chest or paunch measurements. They were 0.18 between production and area of chest and 0.23 between production and area of paunch. Measurements most highly correlated with production were body length (0.31), height at withers (0.35), and depth of paunch (0.36). Multiple correlation coefficients between different sets of measurements and fat production did not exceed 0.40. Measurements of external and internal anatomy were studied on 146 Holstein cows that had been measured before and after slaughter. Depth of chest was significantly correlated with internal chest depth (0.69), heart weight (0.57), and lung weight (0.32); depth of paunch with liver weight (0.48), stomach weight (0.38), length of small intestines (0.31), length of large intestines (0.37), and length of total intestines (0.36). Height at withers showed significant correlations with heart weight (0.50) and lung weight (0.28); body length with heart weight (0.49) and length of intestines (0.34). Partial correlations, with empty body weight held constant, showed that the correlations between certain external and internal measurements were a result of the common association with body weight. The relationship between size of internal organs and fat production was studied on 115 Holstein cows. Correlations were significant only in the case of length of large intestines (0.29) and length of total intestines (0.25). The correlation between depth of paunch and butterfat production was partitioned into a direct component and a component contributed by the association between depth of paunch and organs of the digestive tract. The contribution of the direct path from depth of paunch to fat production amounted to at least 35% of the total correlation. The findings do not support a general supposition that correlations between external body measurements and production are a result of interrelationships with size of internal organs.

Variation in Milk Fat Production in State-Owned Herds in Iowa1,2

Summary This investigation was of 12,623 records made by 4,487 cows from 1940 through 1956 in 12 state-owned herds in Iowa. Herd differences and herd-by-year interactions were responsible for about 6 and 10% of the total variance, respectively. Years, seasons, and the other interactions among these three mainly environmental factors were of minor importance individually; together they accounted for 4% of the total variance. The records were corrected for the major environmental effects by taking each record as a deviation from the average of all records made in that herd in that same year. Then, for obtaining sire and dam components, etc., only the cows whose sires and dams each had at least two daughters in the herd were used. This analysis involved 7,003 records by 2,398 daughters of 295 sires and was made in three different ways: (1) hierarchal classification of sires, dams within sires, etc.; (2) full sister analysis; and (3) cross classification by sires and by dams. Four times the sire component in the first method gave 0.16 as the intraherd heritability of differences in butterfat production. By the second method, twice the full sister component gave 0.12 as the estimate. By the first method 1.6% of the total variance was attributed to dominance deviations and other things, such as maternal effects, that make full sisters resemble each other more than twice as much as paternal half-sisters. In the cross classification, the component for sire-by-dam interaction was 1.8%. These results suggest that deviations from the additive scheme of inheritance are unimportant, but these estimates of nonadditive genetic effects were not precise.

Variations in Certain Blood Components of Holstein and Jersey Cows and their Relationship to Daily Range in Rectal Temperature and to Milk and Butterfat Production

Summary Winter and summer blood samples were taken from 96 Jersey and 78 Holstein cows. Laboratory determinations of the levels of reduced glutathione and hemoglobin and of red-cell volume were made. The data were analyzed statistically to determine all correlations of possible interest and meaning, to determine the relative importance of various assumed causes of variation in the blood components and in daily range in rectal temperature, another variable of interest observed on cows in milk during the summer. All of the blood components were significantly repeatable. Age variation seemed to have no influence on variation in the blood components or daily temperature range. Breed and season differences were significant, but significant sire differences were not observed, except in the case of glutathione in the Holstein breed. Stage of lactation and/or stage of gestation appears to have an influence on or be related to hemoglobin and daily temperature range, stage of lactation being the more important in Jerseys and stage of gestation the more important in Holsteins. Correlations of the blood components with most probable performing ability for milk production, fat production, and fat test were so small that the blood components were concluded not to be useful criteria of selection for these economic traits.

Heritability, Genetic and Phenotypic Correlations of Type, Certain Components of Type, and Production of Brown Swiss Cattle

Summary The heritabilities of final type and eight components of type were estimated by doubling the intra-sire regression of daughter's single type score on dam's single type score from 3,161 daughter-dam comparisons by 294 sires. The heritability estimates were: General appearance .33, dairy character .30, body capacity .23, rump .36, feet and legs .19, mammary system .23, fore udder .28, rear udder .35, and final type .35. The average within-sire phenotypic and genetic correlations between final type, all combinations of the components of type, and butterfat production were estimated from single type and butterfat records. Records on 3,161 daughter-dam pairs were used to estimate genetic correlations, and records on the 3,161 daughters were used to estimate phenotypic correlations. The various genetic correlations between the components of type were positive and relatively large, indicating that positive selection can be made for these components of type simultaneously. The genetic correlation between final type and butterfat production was .24, indicating that selection on the basis of type alone should automatically bring about some genetic improvement in production.

Effect of Varying Alfalfa Hay–Concentrate Ratios in a Pelleted Ration for Dairy Cows

Summary Pellets containing finely ground alfalfa hay and a grain-type concentrate in various ratios depressed butterfat production below normal. The effect was more marked when the rations contained 30 and 45% of concentrates than when no concentrate or when only 15% was used. The increased energy intakes associated with the higher levels of concentrate feeding were not reflected in increases of energy output as measured by 4% fat-corrected milk, apparently due to lower fat production. Live weight gains were not influenced by differences in energy intake. The health and condition of the cows appeared to be satisfactory during the relatively long period (175 days) of feeding only pellets.

A Comparison of Dairy Sire Progeny Tests Made at Special Danish Testing Stations with Tests Made in Farmer Herds

Summary The data consisted of the first-lactation milk and butterfat records of 5,454 daughters of 305 Red Danish Milkrace sires tested at the Danish bull testing stations and the first test-year milk and fat records of 3,270 daughters of 110 of these same sires tested in farmer herds. All records were expressed in kilograms. For the test station data, the components of variance associated with differences between sires within stations and years were 229 for butterfat and 107,652 for milk. The corresponding components for field data after removing herd differences were 71 and 40,540. After expressing each daughter's record as a deviation from its contemporary herd average, the corresponding components were 53 and 32,125. The within-sire components for butterfat were 1,280, 970, and 916, respectively, for the three methods, and 541,696, 513,697, and 527,477, respectively, for milk. The heritabilities resulting from the three methods, assuming that the sire component is wholly genetic, are 0.66, 0.29, and 0.23 for milk and 0.61, 0.27, and 0.22 for butterfat, respectively. One might expect the estimates of heritability obtained from test station data to be somewhat higher than those obtained from field data, but not nearly so much higher as was found in this study. It is concluded that the estimates based on test station data are higher mainly because environmental differences at the same test station in the same year are confounded with progeny groups, thus putting much environmental variance in the sire components and increasing them more than the within-sire components. The estimates of the genetic correlation between station tests and field tests were 0.68 for milk and 0.75 for butterfat. On the other hand, the genetic correlations between independent field tests were 0.94 and 0.92 for milk and butterfat, respectively. This suggests that there is either a large interaction between sires and level of management or that the between-sire components from test station data are inflated with environmental differences. The latter cause is a more logical explanation, as the present data and previous data indicate that the interaction between sires and herds is small. For a constant number of daughters per sire of five or more, the regression of a future daughter in farmer herds on a test in farmer herds exceeds the regression of a future daughter in farmer herds on a test at the test stations. This is true for both milk and butterfat. As the number of daughters per sire increases, the regression based on a field test becomes increasingly larger than the regression based on station tests. For example, for ten daughters the former is 1.44 and 1.48 times the latter for milk and butterfat, respectively; whereas, for 20 daughters the former is 1.73 and 1.75 times the latter for milk and butterfat, respectively. The expected genetic superiority of future daughters, in farmer herds, of sires chosen on a basis of progeny tests is b y'x ( z/b ) σ x for station tests and b y'r ( z/b ) σ y for field tests. Assuming that the same percentage of sires is saved as a result of each system of testing, field tests and station tests can be compared. In the case of milk, if the number of daughters per sire is seven or more, then the expected genetic superiority resulting from selection based on field tests is greater than that resulting from station tests. If the number is less than seven, then the reverse is true. In the case of butterfat production, selection on field tests is superior to selection on station tests if the number of daughters is 15 or more. If the number is less than 15, then the reverse is true. As the numbers increase from seven and 15, the superiority of the field test increases for both milk and butterfat. For 20 daughters per sire, the expected genetic improvement from selection based on field tests is 1.14 and 1.02 times that resulting from station tests for milk and butterfat, respectively. In general, the field tests seem to be superior to station tests if the number of daughters per sire is 15 or more. This superiority increases as the number of daughters per sire increases. In areas where a high percentage of herds is on test there appears to be little need for special dairy sire progeny-testing stations. Assuming that the environmental differences confounded with sires can be controlled by proper experimental design and station operation, and that the expense of operating stations need not necessarily be high, the most serious limitation of test stations is the number of sires that can be tested. To make the expected genetic gain from selection based on tests at special test stations higher than that now expected, more sires should be tested with fewer daughters per sire.

Associations Between Service Interval, Interval from First Service to Conception, Number of Services per Conception, and Level of Butterfat Production

Summary The interval from first service to conception decreases as the service interval increases from 0 to 127 days, at which it reaches a minimum. After a service interval of 127 days, the interval from first service to conception increases slightly as the service interval increases. The length of the service interval accounts for only 1.4% of the variance of the interval from first service to conception; thus, even though its effect on the interval from first service to conception is significant, its effect is small and of little importance. Service interval does not significantly affect the number of services per conception and accounts for only 0.3% of the variance of services per conception. In general, the number of services per conception (Y) decreases linearly as the service interval (X) increases, the partial regression of Y on X for a constant butterfat production being −0.0034±0.0023. The partial regressions of the number of services per conception and the interval from first service to conception on butterfat production for a constant service interval are +0.003±0.001 and +0.091±0.046, respectively, and are significant at the 0.05 level of probability. The partial regression of the number of services per conception on butterfat production for a constant service interval and constant interval from first service to conception is −0.00004±0.0007 and is not significant. It is concluded that there is no real biological relationship between services per conception and level of butterfat production. The service interval alone accounts for 16.8% of the variance of the interval from calving to conception. The interval from calving to conception increases at an increasing rate as service interval increases to approximately 50 days. After a service interval of 50 days, the interval from calving to conception increases almost linearly and in an approximate 1 to 1 ratio as the service interval increases. Calving interval has approximately the same relationship to service interval as has the interval from first service to conception. With the present data, the average service interval must be from 36 to 49 days to maintain an average calving interval of approximately 365 days. If the conception rate was increased to 60%, the average service interval allowed could be increased approximately 11.5 days, and a calving interval of approximately 365 days could still be maintained.

Genetic Structure of Dairy Cattle Herds in Terms of Additive and Dominance Relationships

Summary These data indicate that the average additive relationship within herds is low. The dominance relationship is so low as to be essentially zero. Regardless of the magnitude of the dominance variance, and the variance due to interallelic interactions involving both genes of at least one pair, these components could, on the average, contribute little to the total genetic covariance between relatives in populations which approach so closely the breeding structure of random-mating populations. Also, the genetic differences between the herds which arise from the relationship of contemporary animals indicate that for butterfat production the heritability of differences between herds averages is of the order of 5%, when differences in ideals and intensities of selection are not considered.

Genetic and Environmental Portions of the Variation among Herds in Butterfat Production

Summary The genetic part of the variation between herds has been estimated. In Method A the intra-sire regression of heifer production on herd average is used; whereas, in Method B, the variance components for herd differences between related and between unrelated cows in different herds are compared. Both methods imply that the genetic part of the differences between herd averages is caused entirely by additive gene effects. Evidence from the literature, though scanty, indicates that this is a good approximation. Method A was applied to records of 1,072 Jersey HIR cows and of 880 Holstein DHIA cows. The results indicated that 14 and 10%, respectively, of the differences between herd averages in the two populations are heritable. Prediction equations which utilize both individual performance and herd average are developed. Selection according to these indexes should be 1.19 and 1.35 times as effective as selection based on individual performance alone, without reference to herd averages, in the Jersey and the Holstein population, respectively. Method B was used on records of 2,903 artificially sired Holstein DHIA heifers and of 735 of their dams. When the variance components were derived from an analysis within years, the heritability of herd differences was 6.5%, both for milk and butterfat production. When the analysis was within year-seasons, the resulting heritability estimates were much higher (28 and 24%). It is suspected that the large size of the latter estimates results from sampling variation and, therefore, that the latter values are too large.

Use of High-Nitrogen Feedstuff Made from Whey in the Rations of Dairy Animals1,2

Summary Feeding trials have been conducted to evaluate a high-nitrogen whey derivative as a feedstuff for dairy cattle. Preliminary trials indicated that the product was not toxic and appeared to support growth of 6-mo.-old calves. In one trial, two groups of eight lactating Holstein cows were used in a single-reversal experiment consisting of two 8-wk. periods. All cows were fed grass silage, timothy hay, and a concentrate mixture according to body weight and milk production. The experimental variable consisted of the presence or absence of the whey product in the concentrate mixture at the 10% level. Milk and butterfat production by cows fed the whey product was lower than that of controls, especially during the first period of the experiment. While receiving the whey product, the cows lost significantly more body weight than while on the control ration. Feed refusals by cows fed the whey product were significantly greater than those of control cows, and nutrient intakes of cows fed whey products were below requirements, due to the unpalatable nature of the product. Variations between individuals were noted, with regard to acceptance. It is believed that the portion of the feedstuff actually consumed was well-utilized. No significant differences were noted in blood glucose or blood lactic acid concentrations. In a second trial, 15 male Holstein calves were fed from six days to 20 wk. of age on calf starters which contained 0, 5, or 8% of the whey product. Growth by the three groups of calves was similar, those receiving the 5% level weighing slightly more at 20 wk. than did the other two groups. Consumption of the 5% starter was good, but the 8% mixture apparently lacked in palatability.

The Relationship of Stable Fly Abundance to Milk Production in Dairy Cattle1

Intensive studies, involving two distinct procedures, conducted over a period of 3 years (1955–57) developed very significant correlations between stable fly (Stomoxys culcitrans (L.)) abundance and reductions in milk and butterfat production during the summer months (May-September). On the basis of two distinct regression lines, average monthly rates of loss were established as 0.65 and 0.7% per fly per cow. Evidence is presented indicating that depressed production continues for weeks or months beyond the end of the fly season. Thus good stable fly control for 4 months may produce significant benefits for 6 months or longer.

Twinning in Dairy Cattle and Its Relation to Production

Summary In these data, twin births were 2.91% of the total births. The frequency of identical twins among like-sexed pairs was estimated to be 8.6- 1.1%. The average lifetime production of dams of twins was 19.3 ± 8.9 lb. of butterfat higher than the average production of all contemporary herd-mates. Because frequency of twinning increases with age of dam, this comparison is biased by early culling and selection. Cows removed from the herd after one or two records do not have as much chance to beeome dams of twins as those cows which are kept for many lactations. When dams of twins were compared with contemporary herd-mates which remained in the herd equally long, the difference was only 3.0 ± 5.6 lb. The butterfat production in the lactation following the birth of twins was 21.0 ± 11.0 lb. lmver than in tile lactation immediately preceding this birth. This we consider an estimate of the amount by which the production following the birth of twins is lowered by the physiological extra load, or strain, of producing twins.

Effects of Dietary NaF on Dairy Cows. II. Effects on Milk Production

Summary A study of the tolerance of lactating cows to added dietary increments of a soluble fluoride (NaF) over a 5 1/2-yr. period has been made. The results indicate that under adequate nutritional and husbandry conditions, levels of 50 p.p.m. of fluorine fed as NaF produced no direct deleterious effect upon milk secretion. Sustained fluorine ingestion, with average intake levels of 1.5, and peak intakes of 1.7 or more, mg. of F/kg body weight, led to a reduction of milk and butterfat production in certain cows, as the result of anorexia toward NaF-containing feed, which was accompanied by excessive weight loss and stiffness in the legs. These results indicate further that the effect of fluorine fed in the form of NaF on milk production was a secondary effect conditioned by a curtailed feed intake. The cows in this study tolerated 30 p.p.m. fluorine in their ration, whereas 40 p.p.m. was apparently near the marginal zone of tolerance and 50 p.p.m. in the ration resulted in the development of fluorine toxicosis. The addition of calcium reduced the toxicity of the added NaF. A latent period of from 2 to 5 yr. elapsed between the time the fluorine effects were first noticed on the incisor teeth and the development of other physiologic effects, including the inhibition of milk production. Thus, these studies contribute further evidence to show that the development of fluorine toxicosis is a function of the duration of exposure (time), as well as of level of ingestion. Prolonged dry periods allowed sufficient recovery from debilitating fluorosis for subsequent normal lactation and milk production.

Repeatability of Dairy Cow Butterfat Records in New Zealand

Summary Three different approaches were used to estimate repeatability and, correspondingly, three different interpretations are placed on the results. In the first analysis, where a herd variance component was taken into account, year effects were considered to be random, and found to be negligible–the herd-by-year effects absorbing all the year variations. In this analysis, repeatability (0.65) is applicable to any cow, relative to an over-all average for the whole country, and as such is not very useful. In the first of the within-herds analyses, years were treated as mere replications and repeatability (0.49) is relative to a general herd level, regardless of year. In the final analysis, year effects were eliminated, and repeatability (0.61) then applies to the deviation of a cow's records from her herd average in the same year. The increase from 0.49 to 0.61, when yearly effects are taken into account, indicates the importance of the within-herd, year-to-year variation, when considering repeatability estimates. Within-herd estimates of repeatability obtained here are higher than earlier estimates, probably due to the fact that only four years are represented. It is probable that the decrease in correlations as the time interval increases (shown in Table 1), is due to long-term effects which are not likely to be directly associated with a cow's genetic make-up for butterfat production. Therefore, in using repeatability to estimate the “true producing ability” of a cow in a particular herd, there is valid reason for using the higher values based on the short-term analysis.

Genetic and Environmental Factors in the Development of the American Red Danish Cattle1,2

Summary Genetic and environmental factors in the development of the American Red Danish cattle were investigated. The intrasire regression of production on inbreeding was −23.1lb. milk and −0.3lb. butterfat for each additional 1% of inbreeding. Two lethal defects, paralyzed hind quarters and ankylosis, appeared in the second cross to Red Danish sires. Calf mortality and cow sterility apparently increased with successive crosses. Heritability of butterfat production was estimated as 0.39±0.11, repeatability as 0.43. Average adjusted butterfat production in the foundation, first-cross, second-cross, and third-cross generations was 351, 379, 377, and 389lb., respectively. Butterfat yield did not vary significantly with month of calving but increased 2.0lb. (P

Genetic Analysis of the Components of Type Conformation and Production in Ayrshire Cows1,2

Summary The heritabilities of ten components of type and final rating were estimated from approximately 1,180 daughter-dam comparisons by doubling the intraherd regression of daughter's single type score on dam's single type score. The heritability estimates are as follows: head and neck, 0.30; shoulders and chest, 0.15; middle and loin, 0.31; rump and thighs, 0.32; feet and legs, 0.18; udder size and shape, 0.08; udder attachments, 0.06; udder teats, veins and quality, 0.27; general quality, 0.13; breed character, 0.32; and final rating, 0.31. Single type and butterfat records were used to estimate the average within-herd phenotypic and genetic correlations between all combinations of the components of type, final type rating, and butterfat production. Records on 1,273 cows were used to estimate phenotypic correlations, and 729 daughter-dam pairs were used to estimate genetic correlations. The phenotypic correlation between final type rating and butterfat production was estimated to be 0.08, and the corresponding genetic correlation was estimated to be -0.52. From these rather limited data and because of the sampling error involved, the estimates of genetic correlations can only be considered as approximate. Even so, it seems that the genetic correlations between butterfat production and final type rating and between butterfat production and the components of type are low at best. The weights which should be given to the records on each component of type and a single butterfat record on an animal when selecting for butterfat production were determined. These data indicate that in selecting for butterfat production alone nothing can be gained by giving positive emphasis to final type score.

The effect of undernutrition after calving on the quantity and composition of the milk produced by dairy cattle

Fourteen pairs of monozygous twin cows of mixed ages were used to determine the effect of underfeeding from the 3rd to the 8th week inclusive after calving on milk and butterfat production and on the composition of the milk.Those cows which were well fed over the 6-week period produced more milk and a larger weight of butterfat than their sisters which had been poorly fed. The milk from the well-fed cows had a lower percentage of butterfat, but higher percentages of solids-not-fat and total protein, than the milk from the poorly fed cows.The complete lactation averages failed to show statistical significant differences in all characteristics except in the case of solids-not-fat percentage. The mean difference between the two groups for solidsnot-fat was found to be highly significant.In general, the results support the conclusions of other workers, that underfeeding dairy cows may depress the solids-not-fat content of the milk.It appeared that differences between the two groups in butterfat percentage over the 6-week experimental feeding period were strongly correlated with differences in weight changes and that the small amount of variance associated with milk yield differences was not significant.