Journal of Dairy Science 

About: Journal of Dairy Science is an academic journal. The journal publishes majorly in the area(s): Dairy cattle & Lactation. It has an ISSN identifier of 0022-0302. Over the lifetime, 33365 publication(s) have been published receiving 1194976 citation(s).

Methods for dietary fiber, neutral detergent fiber, and nonstarch polysaccharides in relation to animal nutrition.

Abstract: There is a need to standardize the NDF procedure. Procedures have varied because of the use of different amylases in attempts to remove starch interference. The original Bacillus subtilis enzyme Type IIIA (XIA) no longer is available and has been replaced by a less effective enzyme. For fiber work, a new enzyme 1 1The heat stable amylase, formerly Number 5426, has been changed by Sigma as of July 1991. The original procedure required .2 ml of this enzyme. The replacement. Number A3306, is four times stronger, and 50 μl are used per sample. has received AOAC approval and is rapidly displacing other amylases in analytical work. This enzyme is available from Sigma (Number A3306; Sigma Chemical Co., St. Louis, MO). The original publications for NDF and ADF (43, 53) and the Agricultural Handbook 379 (14) are obsolete and of historical interest only. Up to date procedures should be followed. Triethylene glycol has replaced 2-ethoxyethanol because of reported toxicity. Considerable development in regard to fiber methods has occurred over the past 5 yr because of a redefinition of dietary fiber for man and monogastric animals that includes lignin and all polysaccharides resistant to mammalian digestive enzymes. In addition to NDF, new improved methods for total dietary fiber and nonstarch polysaccharides including pectin and β-glucans now are available. The latter are also of interest in rumen fermentation. Unlike starch, their fermentations are like that of cellulose but faster and yield no lactic acid. Physical and biological properties of carbohydrate fractions are more important than their intrinsic composition.

Efficient Methods to Compute Genomic Predictions

Abstract: Efficient methods for processing genomic data were developed to increase reliability of estimated breeding values and to estimate thousands of marker effects simultaneously. Algorithms were derived and computer programs tested with simulated data for 2,967 bulls and 50,000 markers distributed randomly across 30 chromosomes. Estimation of genomic inbreeding coefficients required accurate estimates of allele frequencies in the base population. Linear model predictions of breeding values were computed by 3 equivalent methods: 1) iteration for individual allele effects followed by summation across loci to obtain estimated breeding values, 2) selection index including a genomic relationship matrix, and 3) mixed model equations including the inverse of genomic relationships. A blend of first- and second-order Jacobi iteration using 2 separate relaxation factors converged well for allele frequencies and effects. Reliability of predicted net merit for young bulls was 63% compared with 32% using the traditional relationship matrix. Nonlinear predictions were also computed using iteration on data and nonlinear regression on marker deviations; an additional (about 3%) gain in reliability for young bulls increased average reliability to 66%. Computing times increased linearly with number of genotypes. Estimation of allele frequencies required 2 processor days, and genomic predictions required <1 d per trait, and traits were processed in parallel. Information from genotyping was equivalent to about 20 daughters with phenotypic records. Actual gains may differ because the simulation did not account for linkage disequilibrium in the base population or selection in subsequent generations.

A Body Condition Scoring Chart for Holstein Dairy Cows

Abstract: A chart for body condition scoring of freely moving Holstein dairy cows was developed using an iterative process consisting of literature review, interviews with experts, field testing, statistical analysis, and comments from chart users. The chart consists of text and diagrams that detail changes in conformation with body condition change for eight body locations identified as important in body condition scoring. The precision with which a prototype chart was used to give location specific condition scores to cows was examined, and the variability among the assessors described. This chart gave consistent results with small variability among assessors, no significant difference attributable to experience of assessors, and no significant cow assessor interaction. Minor modifications were made to the chart, which was then used to assess location specific and overall body condition scores. Assessors scored cows in the eight body locations and rescored the cows in a different order to assign an overall score. The chart produced consistent scores over a wide range of body conditions with small variance among assessors. The overall score was most closely related to the condition scores of the pelvic and tailhead areas of the cow. Both location specific scores within cows and the overall body score for a cow were strongly correlated, demonstrating that the chart was internally consistent. The chart is an effective field tool for body condition scoring Holstein cows.

Partitioning of Nutrients During Pregnancy and Lactation: A Review of Mechanisms Involving Homeostasis and Homeorhesis

Abstract: Control of metabolism during pregnancy and lactation involves two types of regulation-homeostasis and homeorhesis. Homeostasis control involves maintenance of physiological equilibrium or constancy of environmental conditions within the animal. Homeorhesis is the orchestrated or coordinated control in metabolism of body tissues necessary to support a physiological state. Regulation of nutrient partitioning during pregnancy involves homeorhetic controls arising from the conceptus. This assures growth of the conceptus (fetus and fetal membranes) and gravid uterus as well as development of the mammary gland. With the onset of lactation many--perhaps even most--maternal tissues undergo further adaptations to support rates of lipogenesis and lipolysis in adipose tissue are examples of important homeorhetic controls of nutrient partitioning that are necessary to supply mammary needs for milk synthesis. The interactions between homeorhesis and homeostasis during pregnancy and lactation and possible endocrine control are discussed. While not definitively established, roles for placental lactogen and prolactin are attractive possibilities in homeorhetic regulation of maternal tissues to support pregnancy and the initiation of lactaion, respectively.