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One thousand Holstein-Friesian heifer calves were studied to evaluate the effects of colostrum-derived 24 to 48 h serum Ig concentrations on growth and survival. The rate of growth increased as 24 to 48 h serum Ig concentrations increased. Calves born to first-calf heifers had higher 24 to 48 h serum Ig concentrations and gained weight at a higher rate of gain than heifers born to 3-year-old and older cows. The concentration of serum Ig at 24 to 48 h in the dairy heifer is a significant source of variation affecting average daily gain through the first 180 d of life. Seasonal factors were also significant in influencing rate of gain from birth to 6 months. Age of dam was a significant source of variation in calf weight gains, but only for the first 35 d of life. Approximately 28% of the calves absorbed less than 12 mg/ml of maternally-derived antibody. Heifers in this category suffered a death loss of 6.78% compared to only a 2.59% loss for heifers absorbing greater than 40 mg/ml Ig. Both season and age of dam were significant in affecting the concentration of 24 to 48 h serum Ig acquired. Forty-nine percent of the variation in 35 d serum Ig can be attributed to the variation found at 24 to 48 h. The data presented here indicate that proper management of factors influencing the absorption of colostral immunoglobulins by the neonatal dairy heifer would enhance the replacement rearing program.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

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The pattern of post-partum and ovarian activity was monitored in two herds through the use of radioimmunoassay of progesterone in post-milking strippings. The University of British Columbia, South Campus (UBC) herd was sampled on a twice weekly basis, while the Agriculture Canada Research Station, Agassiz herd was sampled every second day. Sampling began approximately six days post-partum and continued up to 60 days post-conception. The estrous cycle was classified into phases based on the concentration of progesterone in the milk samples. Progesterone concentration immediately post-partum and for a varying length of time thereafter remained at basal levels. This was classified as Phase 0 and represented the stage of quiescence in the ovaries post-partum. Phase 1 of the estrous cycle represented the follicular stage when the concentration of progesterone was low. Phase 2 represented the stage when the corpus luteum was developing and the concentration of progesterone was rising. Phase 3, the fully active corpus luteum stage, was when the concentration was highest, while Phase 4 represented the regressing corpus luteum stage when the concentration was falling. The stage of quiescence, from parturition to the initiation of luteal activity was found to be 21.43 ± 11.84 days for 54 animals in the UBC herd and 19.81 ± 8.85 days for 127 animals in the Agassiz herd. Retained placenta increased the duration of quiescence to 25.62 ± 12.41 days for the 12.6% or 16 animals having the condition in the Agassizherd. The 9.3% or five animals having retained placenta in the UBC herd had a much shorter stage of quiescence of 10.80 ± 6.42 days. Two distinct types of first cycles were found, based on the mean concentration of progesterone and the number of days in the period. A normal first cycle exhibited more luteal activity during Phase 3, and remained in this Phase longer than did the shortened first cycle. This may be associated with follicle luteinization in the shortened first cycle rather than true ovulation as in the normal first cycle. The increased frequency of sampling of the Agassiz herd tended to give a more accurate classification of the phases of the cycle as defined, with more Phase 4 samples being identified. Also days in Phase 1 and Phase 2 for both Type 1 (shortened first cycle), and Type 2 (normal first cycle), were approximately half of those observed from the UBC herd. Standard curves of progesterone concentration vs. time for "normal" cycles of various lengths with standard deviations were derived from the pooling of all cycles classed as normal first cycles and normal cycles without a breeding. These "normal" cycles showed that as the cycle length increased, so did time spent during Phase 1 when the concentration of progesterone remained below 4 ng/ml milk. Progesterone profiles of various animals are included, illustrating the wide variety of profiles found. These include profiles of short stages of quiescence, long stages of quiescence, short cycles, long cycles as well as some abnormalities observed. When used as a test for early detection of pregnancy, a single sample from days 21 to 24 for the UBC herd showed accuracies of 100% in determining non-pregnancy and 86% in determining pregnancy. Test results for days 21 and 22 for the Agassiz herd were again 100% accurate for determining non-pregnancy and 90.5% accurate in determining pregnancy. The accuracy of the non-pregnant determination can be increased by including a sample on day of insemination and eliminating those animals inseminated at an obviously incorrect time. With the two sample test on the combined UBC data the accuracy of the pregnant diagnosis increased to 91.5%. On the combined Agassiz data the two sample test increased the accuracy of the pregnant diagnosis to 93.1%. The use of progesterone pregnancy testing offers a considerable saving in time in identifying those animals not conceiving to insemination and a reasonably accurate means of early detection of pregnancy. The average number of days from conception to positive palpation was 51.02 ± 13.19 days for 97 animals in the Agassiz herd and 60.43 ± 23.59 days for the 42 animals in the UBC herd. / Land and Food Systems, Faculty of / Graduate

This study has compared the effect of milk pricing systems on the selection goals of dairy producers in two provinces of Canada, British Columbia (BC), and Quebec. These provinces were chosen for comparison as BC produces milk largely for a fluid market, while Quebec produces milk for a manufacturing market. Within BC, due to a higher utilization and higher milk price, the value/kg of skim on Vancouver Island was higher than that of the Vancouver Lower Mainland over the study period 1963-1982. Between the two provinces, the value/kg of skim in BC was found to be consistently higher than in Quebec over the 20 year period, while the value of fat was higher in Quebec than BC. In BC in 1980, the value of a kilogram of skim was approximately $0.30, whereas its value in Quebec was only $0.20. During the 1960s in BC, the value of skim represented one half the value of milk, and in 1982 it comprised two thirds of the value of milk, as compared to Quebec, where fat represented 43% of the value of milk. Net economic values were calculated by subtracting the dollar cost of production associated with the components of milk (carrier, fat and protein), from the gross value/kg of skim and fat. These values showed that the value/kg of protein was negative and decreasing in both BC and Quebec. The economic value/kg of butterfat has been consistently positive and increasing over the study period in BC and Quebec to $3.27 and $3.34/kg respectively in 1982. The relative economic values of carrier, fat and protein in BC and Quebec in 1982 were 0.08:1.00:-0.10 and 0.06:1.00:-0.12 respectively, which puts moderate selection on carrier and fat, and negative selection on protein. Selection index weights for carrier, fat and protein revealed that the BC dairy industry has always applied positive selection to the carrier and fat portion, and negative selection to the protein portion of milk. In 1982 the selection weights were 0.087:1.253:-1.189. The Quebec index has shown more fluctuation that BC, with less selection against solids compared to BC; (0.050:1.280:-0.657). Theoretical genetic goals of the BC dairy industry have been consistent at approximately 3.0% butterfat, 2.0% protein and 95.0% carrier. The genetic goals in Quebec have undergone wide fluctuations, but generally have signalled the dairy producer to increase both butterfat and protein. The goals of the two industries are now very similar, with the exception that Quebec continues to place higher value on solids than BC. / Land and Food Systems, Faculty of / Graduate

In order to investigate the use of fuzzy logic in decision-support systems (DSS) for dairy cattle breeding, a first-generation prototype software system was developed. The objectives were to determine the advantages and limitations of fuzzy logic for this type of application, and to establish a basis for the development of more complete DSS in the future. The goal of the prototype DSS was to make culling decisions on the basis of monthly production data. An analysis of the development process of this prototype demonstrated the importance of creating a thorough methodology for the elicitation and implementation of knowledge. A framework for the development of fuzzy decision-support systems was established, consisting of four phases: the project groundwork phase, elicitation of knowledge from the expert, implementation of that knowledge, and system validation. In this framework, it is proposed that, in the case of multiple experts, knowledge can be amalgamated or aggregated. Once this framework was established, a second-generation prototype DSS was developed. Contrary to the first-generation prototype, where the encoded expertise was limited to three experts from the same domain, the second-generation prototype considered the knowledge of two individuals from each of three domains (Dairy researchers, Producers, and Dairy herd improvement specialists). An aggregation approach was used which involved the development and maintenance of separate modules, each containing the compiled expertise of one of the six experts.

Crossbreeding parameters (additive (a), dominance (d) and additive x additive (aa) epistatic effects for individual $ sp{ rm (I)}$ and for maternal $ sp{ rm (M)}$ performance) on body weight growth and first lactation performance traits of females from a crossbreeding experiment between Holstein (H) and Ayrshire (A) based lines were estimated by individual animal models, incorporating all known additive genetic relationships amongst animals, through restricted maximum likelihood and mixed-model methodologies. / The growth traits (asymptotic weight (A), rate parameter (k), inflection parameter (m), average lifetime absolute growth rate (AGR), average lifetime absolute maturing rate (AMR) and average lifetime relative growth rate (RGR)) were estimated by fitting the nonlinear equation, W$ sb1$ = A(1 $ pm$ be$ sp{ rm -kt}) sp{ rm M}$, to the observed weight-age data of 3076 individual females. / Results from the analyses of growth traits indicated that the H line exceeded the A line in addition genetic effects for individual performance (a$ sp{ rm I}$) for both A and AGR. The H line also exceeded the A line in additive effects for maternal performance (a$ sp{ rm M}$) in trait A. Both dominance (d) and additive x additive (aa) epistatic effects were statistically important in most cases. Individual heterosis (h$ sp{ rm I}$ = d$ sp{ rm I}$ $-$ 0.5aa$ sp{ rm I}$) was positive for traits A and AGR, whereas maternal heterosis (h$ sp{ rm M}$ = d$ sp{ rm M}$ $-$ 0.5aa$ sp{ rm M}$) was negative for A and positive for AMR. Total heterosis (TH = h$ sp{ rm I}$ + h$ sp{ rm M}$) had positive effects on AGR and AMR. For all growth traits, heterosis retained in advanced crossbred generations was statistically irrelevant. The overall conclusion was that crossbreeding systems designed to capitalize on TH would produce faster growing and earlier maturing animals. / The analyses of production traits found the additive effect of the H line for individual performance to be a major factor to increase yields of milk, protein and fat. On the other hand, line maternal and cytoplasmic source tended to favour the A line, but none reached statistical significance in any of the traits. Results indicate that two-line specific crosses or synthetic development would be sound breeding strategies for taking advantage of first cross heterosis or of line additive differences, respectively. / Estimates of crossbreeding parameters from mixed-model analyses, were found to be more reliable than those from ordinary least squares analyses. (Abstract shortened by UMI.)

Please read the abstract in the section 00front of this document / Dissertation (M Inst Agrar (Animal Production Management))--University of Pretoria, 2006. / Animal and Wildlife Sciences / unrestricted