Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 11 of 11 for “"age at first calving"”.
-
Influence of Prepubertal Dietary Protein and Age at First Calving on the Performance, Reproduction and Lactation of Replacement Beef Heifers
The objective of this research was to evaluate the effects of prebreeding dietary protein level and age at first calving on the performance, reproduction and lactation of replacement beef heifers. Dietary protein levels ranging from 11.7% to 22.6% CP were tested in six experiments using several …
-
Comparisons of Holstein, Brown Swiss, and Jersey cows for age at first calving, first calving interval, and true herd-life up to five years in seven regions of the United States
The objectives of this research were to evaluate breed differences for heat-stress resistance using age at first calving and first calving interval, and to assess breed by region interactions for seven regions of the United States for survival-related traits up to five years of age in Brown Swiss, …
-
Effects of Calfhood Respiratory and Digestive Disease on Calfhood Morbidity and First Lactation Production and Survival Rates
Calf health data and first lactation records for 2556 cows born in a commercial dairy herd between June 1998 and June 2001 were studied to determine the effects of calfhood disease on survival and performance. Operator-treated respiratory disease occurrences within the first year of life and …
-
Genotype by environment interaction for Holstein milk yield and fitness traits between Saudi Arabia and the United States
… components and genetic parameters for Holstein first and all lactations mature equivalent milk and reproductive traits in the first four lactations were estimated by multiple-trait animal model using Method R procedures. The objectives of this study were to determine if genotype by environment …
-
Microcomputer simulation of management practices affecting timing of net income in dairy cattle
Microcomputer simulation was used to evaluate effects of all combinations of two levels of involuntary culling, heifer rearing, and sire selection against dystocia in heifers on timing and magnitude of net income in dairy cattle. Time to cumulative payoff of expenses and net income per day of …
-
Efeito do cromossomo x no mapeamento de regiões genômicas sobre características de interesse econômico em búfalos da raça murrah
… in the buffalo genome, containing many genes that can influence the expression of economically important traits. However, in current GWAS studies, researchers almost exclusively use molecular markers from autosomes, excluding the sex chromosomes. Thus, the aim of this work was to identify …
-
Aspectos reprodutivos de coelhas da raça Lion Head
Rabbit breeding is an important practice for generating income for small farmers. In recent years there has been a considerable increase in the number of pet rabbits, also known as pet. The production of these animals is of great relevance for the Brazilian Cunicultura, since it corresponds to a …
-
Relationships between first lactation milk yield, first calving interval, herd life, lifetime milk production, and descriptive type subtraits in Holstein cattle
Descriptive type classification data recorded by the HolsteinFriesian Association of America was compared to DHIA production data to determine which of the type subtraits were related to first lactation production, first calving interval, herd life, and lifetime milk and fat yields. Variables other …
-
A Microcomputer Simulation to Evaluate Management Strategies For Rearing Dairy Replacements
A microcomputer simulation was developed as a tool for analyzing the dairy replacement enterprise. The simulation was constructed using a spreadsheet, and equations were developed using stepwise regression procedures. The simulation predicted BW, DMI, and fixed and variable costs for each week of a …
-
Genetic Parameters for Udder and Teat. Type Traits in Icelandic Cattle Breed
Udder balance, fore udder attachment, udder support, udder depth, teat structure, teat length, teat thickness, teat position and teat tip of Icelandic Cattle have been described on a linear scale since 1995. Udder and teats now weigh 20% in Icelandic Cattle’s total merit index, but udder balance, …
-
Development of a multi-breed heifer pregnancy genetic evaluation in beef cattle
… of a beef cow-calf enterprise. Reproductive rates determine the number of calves born and thus influence the amount of beef product produced at the commercial level driving income for cow-calf operators. Heifer fertility then is an economically relevant trait, though in most cases pregnancy …