This study used DHI records of 1,023,827 Holstein cows to determine the impact of adjusting measures of profit for opportunity cost and for evaluating the impact of herd-year variables and registry status on measures of profit. Relative Net Income (RNIJ) and RNI including opportunity cost (RNIOC), the revenue forfeited that could have been generated by a replacement heifer, were calculated for 48 month, 60 month, 72 month, and all lactations herdlife period. Application of opportunity cost caused a decreased value for length of herdlife. Number of lactations initiated prior to the various herdlife periods was the criteria for deciding how much information was included in each of the herdlife periods. Opportunity cost per day (OCPD), the revenue forfeited that could be earned by replacement, was calculated by regressing herd-year means for RNI and days of productive life (DPL) on overall herd means based on the number of animals in herd-years, and dividing the regressed mean for RNI by the regressed mean for DPL. RNIOC for each herdlife period (i) was calculated as RNI(i) - (OCPD(i) * DPL(i)) for each cow in a herd-year. Application of OCPD removed all of the variation due to herd and year for RNIOC. Standard deviations and means were smaller for RNIOC than for RNI. This was because there were fewer animals with extremely large values for RNIOC than for RNI. These differences increased as herdlife period advanced. The correlation of RNI and RNIOC to 72 mo herdlife was .95. This was caused by a lower correlation with DPL for RNIOC than RNI (.73 vs. .84). First lactation yield had similar correlations with both measures. Regression analysis showed all of the year within herd variance for profit measures and no error variance could be explained by herd management variables, with average first lactation milk dominating. Grade cows were lower than registered cows for profit measures within herd, and differences increased as herdlife period advanced. / Master of Science

The ability of mammary tissue from mature Holstein bulls to respond to hormonal stimuli in organ culture to synthesize and secrete milk proteins was studied. Sixteen bulls from the genetic selection and control lines developed at Virginia Polyteclmic Institute were randomly assigned to either a non-treated or steroid pretreated group. The steroid pretreated group received estradiol 17-B and progesterone at 0.1 and 0.25 mg/kg/day, respectively, for 7 d starting 15 d before slaughter. Mammary tissue was explanted and cultured for up to 96 h in basal medium (B) which consisted of Media 199 supplemented with fetal calf serum and bovine insulin, or stimulatory medium (St), which was further supplemented with triiodothyronine, estradiol 17-B, hydrocortisone, and bovine prolactin (PRL). Explants in duplicate multi-well culture dishes were incubated in the presence of 3H-Iabeled amino acids or 3H-Iabeled thymidine. Measurements made included: casein in media and homogenized tissue, alpha-lactalbumin in homogenized tissue, tri-chloro-acetic acid precipitable 3H-protein in media and homogenized tissue, and DNA content of cultured tissue. A subset of cultured explants from each bull was fixed and embedded for histological evaluation and auto radiographic localization of incorporated 3H-labeled thymidine. Synthesis and secretion data, as well as growth responses of the epithelium were compared between selection and control bulls. / Master of Science

Two experiments with dairy cows during early lactation were conducted to determine the effects of feeding feather meal and fat. The objective of Experiment 1 was to determine milk production, milk composition, feed intake, and concentrations of AA and long chain fatty acids in blood plasma. Thirty two Holstein cows began a six week trial at the start of the fourth week of lactation. Diets included a control diet (51% forage, 49% concentrate, 16.8% CP, and 19.1% ADF) and diets containing 2.2% feather meal, 3.6% supplemental fat (hydrogenated tallow), or feather meal plus fat. Feather meal and supplemental fat were substituted for soybean meal and corn grain, respectively, in the control diet concentrate. For Experiment 2, four lactating Holstein cows (15, 20, 21, and 65 d postpartum) with ruminal and duodenal cannulae were used in a 4X4 Latin square design (21 d feeding periods) to determine digestibilities of the four diets. The markers used to estimate digesta flow were Co- EDTA and chromic oxide. When cows were fed feather meal, milk fat % was higher, milk protein % was lower, and plasma total essential AA were increased. Dry matter intake, milk production, and plasma long chain fatty acids increased when cows were fed diets containing fat. Differences between concentrations of AA in the tail artery and mammary vein indicated significant uptake by the mammary gland. The mammary gland extracted approximately 36% of the total essential AA in plasma. Intake, duodenal flow, and ruminal and total tract digestibilities of DM, ADF, N, and OM were similar for all diets. No changes were seen in rumen pH, rumen ammonia-N, VFA's, or rumen bacteria AA. Intake and fecal output of total, essential, and non-essential AA were greater when cows were fed diets containing feather meal. However, flow of AA to the duodenum, AA absorbed, and AA digestibilities did not differ. Results suggest that bypass proteins with a complimentary EAA profile must be fed with feather meal to compensate for the low amounts of Lys, Met, and His provided by feather meal. / Master of Science

Complete data is given of a digestion trial made with two Holstein cows, one being feed maintenance ration plus protein, the other maintenance ration plus carbohydrate. The digestive co-efficient of both cows were about normal. The cow which received the maintenance ration plus B. Albumen digested 67.87% of whole ration and the one which received maintenance ration plus carbohydrate digested 66.10% of whole ration. Both of which is a little lower than the theoretical. The following authorities have been consulted: Echol’s Missouri Station Bulletin Research 2 and 5. Henry’s, Shermans, Armsby’s, and Farmers Bulletin 346. Bulletin 22 Revised Department of Agriculture. / Master of Science

De Kol 2d, Pietertje Hengerveld and Belle Koendyke each have two daughters. For each daughter the following number of grand daughters are found. For Belle Korndyke 93.5, De Kol 2d 81.5 , and Pietertje Hengerveld 60.5. The following number of great-grand-daughters may be attributed to each grand-daughter: De Kol 2d 5.29, Belle Korndyke 3.11 and Pietertje Hengerveld 2.96. This shows De Kol 2d was more prepotent over her great-grand-daughters or her daughters were bred to better sires. The percent of the progeny found in each class clearly shows the prepotency of the progenitor. The most noticeable influence over the grand daughters of the first class was that of Belle Korndyke, having 16.52% of progeny in first class. De Kol ranked second and Pietertje Hengerveld third. In class two Belle Korndyke ranks first, De Kol 2d second, and Pietertje Hengerveld third. In classes three and four some change is order is noticeable; Pietertje Hengerveld ranks first, De Kol 2d second, and Belle Korndyke third. / Master of Science

Data sets from six locations containing 631 dairy heifers and 5409 observations of individual dry matter intake (DMI) were used to develop an equation to predict DMI. Data were contributed by Pennsylvania State University, University of New Hampshire, Purina Mills, Kansas State University, University of Minnesota, and Virginia Tech. Objectives varied by location and trials within locations but all contained DMI (kg/d), BW (kg), age (wk), DM, and CP, and ADF percentages of ration DM. Daily gains (g) were calculated from consecutive BW. Season was expressed as sine wave of Julian day plus 60 d times Ï divided into 180. Average daily temperature, humidity, and wind data were collected from Minnesota and Virginia and analyzed with BW to determine their effect on DMI. Sire PTA milk, protein, and fat of heifers were recorded from all sources to determine the relationship of genetics with DMI. Diet measurements (DM, CP, and ADF percent of ration DM) were analyzed with BW to determine their impact on DMI. Two equations were developed using backwards elimination techniques. The first equation was: DMI = -12.63 + .0587(BW) - .0000264(BW2) - .000 12(BWxDM) - .000477(BWxADF) + .292(DM) - .00103(DM2) - .413(CP) + .01349(CP2) + .181(ADF) - .0025(DMxCP) - .00269(DMxADF) + .00509(CPxADF) with an R2 of .90. Because body weight and diet variables were highly correlated, a smaller model could be created with one diet variable. A smaller model would also be more practical to use if accuracy was not lost. Body weight and ADF were used for second model: DMI = -1.71 + .0429(BW) - .0000246(BW2) - .00023(BWxADF) + .032(ADF) - .00068(ADF2) with an R 2 of .87. Previous DMI prediction equations from Virginia Tech were validated using all data from other locations and had R2 of .90 and .84 with this data set. Body weight raised to the .53 power most accurately described the relationship of DMI and BW. Temperature and DMI had a quadratic relationship. Higher DMI were observed at extreme temperatures between -10 to 27° C. Humidity and temperature x humidity accounted for more variation of OMI than season and other environmental measures, but were not included in the small model due to availability of these measurements and they did not change OMI by .1 kg/SO. Sire PTA milk by groups showed differences among heifer groups although no trends were found. Dry matter percent and CP percent had linear and quadratic relationships with OMI. Maximum OMI plateaued between 75 and 950/0 OM and occurred at extreme percentages for CP between 9 and 27%. Acid detergent fiber percent had a negative linear relationship with OMI between 7 and 45%. / Master of Science

A total of 114,351 Holstein first lactation records collected by the Quebec Dairy Herd Analysis Service (DHAS-PATLQ) between September, 1979 and January, 1994 were used to study the effects of adjusting records for linear and quadratic effects of 90- and 305-d feed intake measures (total energy, total protein and total dry matter) on estimation of heritabilities of and genetic correlations among yield and composition traits. Genetic parameters of feed intake measures, relationships between feed intake and age and weight at calving, and feed conversion efficiency traits were also examined in a series of studies. A sire model fitted by REML estimated heritabilities of 305-d milk, fat and protein yields, fat and protein percents as .45 +/- .04, .48 +/- .04, .44 +/- .03, .92 +/- .06, and .88 +/- .05, respectively. Correction of 305-d records for differences among cows in feed intake levels reduced heritabilities of milk, fat and protein yields to .35 +/- .03, .52 +/- .04, and .38 +/- .03, respectively. Heritabilities of composition traits (fat and protein percents) remained unchanged. Genetic and phenotypic correlations for yield traits were also reduced (48--170%, and 16--51%, respectively) which may indicate that genetic associations between yield traits are less than what we believed them to be. Heritabilities of 305-d total energy, total protein, total DM intake, grain energy, grain protein, grain DM, base energy, base protein, and base DM were .30 +/- .03, .24 +/- .02, .35 +/- .03, .23 +/- .02, .23 +/- .02, .23 +/- .02, .31 +/- .03, .26 +/- .02, and .40 +/- .03, respectively. Genetic correlations between feed intake measures were very high; they were approaching unity in some cases. Therefore, any one of these feed intake measures can represent the others. A multi-trait REML analysis estimated heritabilities of age and weight at first calving as .11 +/- .01 and .37 +/- .03, respectively. Age at calving was negatively associated with yield traits and with total e

The objective of this thesis was to test for associations between genetic polymorphisms of genes related to immune response (growth hormone (GH), growth hormone receptor (GHR), ornithine decarboxylase (ODC), insuline-like growth factor-1 (IGF-1), adrenocorticotropin hormone (ACTH), corticotrophin releasing hormone (CRH), and prolactin (PRL)) and mastitis resistance traits (incidence of clinical mastitis (ICM), occurrence of clinical mastitis (OCM), culling due to mastitis (CDM), and somatic cell scores (SCS)) in Canadian Holsteins. / Using lactation records of cows enrolled in milking recording in Quebec (Programme d'Analyse des Troupeaux Laitiers du Quebec, PATLQ from 1980 to 1994 (411,291 first, 238,432 second, and 130,983 third lactations, respectively) Estimated Transmitting Abilities of traits were generated with a model that included the random effect of sire, and fixed effects of herd-year-season-of calving, age at calving, and genetic group. 721 bulls which had daughters in the phenotypic data sets were genotyped for twenty polymorphisms of the above genes located on autosomes (BTA) 5, 11, 14, 19, 20, and 23. / Two types of analysis of associations were performed: analysis across-population with a model that included the fixed effect of marker and random effect of the son of grandsire, and within-family analysis with a model that included the fixed effects of the grandsire, marker nested within grandsire, and the random effect of son nested within marker and grandsire. Permutation tests were performed to reduce Type I error probability. / Significant associations were found within families for markers of IGF-1 (BTA5), ODC (BTA11), GH (BTA 19), GHR (BTA 20), and PRL (BTA 23) for ICM, OCM, CDM, and SCS in different lactations. Some of these putative quantitative trait loci (QTL) are located on BTA where other authors have reported QTL affecting SCS and udder conformation. The results from this study may contribute to efforts to dissect the genetic basis of mastitis resistance in dairy cattle.

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