Author
Gabriella A. Varga
Other affiliations: Agricultural Research Service
Bio: Gabriella A. Varga is an academic researcher from Pennsylvania State University. The author has contributed to research in topics: Dairy cattle & Rumen. The author has an hindex of 40, co-authored 89 publications receiving 4240 citations. Previous affiliations of Gabriella A. Varga include Agricultural Research Service.
Papers published on a yearly basis
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TL;DR: The data implicate His as a limiting AA in high-producing dairy cows fed corn silage- and alfalfa haylage-based diets, deficient in MP, and propose that, similar to monogastric species, AA play a role in DMI regulation in dairy cows.
217 citations
TL;DR: Evaluating quantitatively the chemical and physical properties of protein and energy sources that determine AA availability to lactating cows and factors that alter microbial metabolism of N in the rumen and subsequently protein supply to the small intestine are evaluated.
205 citations
TL;DR: Four multiparous Holstein cows fitted with rumen and duodenal cannulas were used and passage of bacterial N to the duodenum was highest when rumen availabilities of both nonstructural carbohydrate and protein were high.
192 citations
TL;DR: The tendency toward higher milk yield for glycerin-supplemented cows during wk 6 of lactation (52 vs. 46 kg/d) after the supplementation period suggested a potential benefit of dry Glycerin on subsequent milk production, perhaps through changes in metabolism, which requires further investigation.
153 citations
TL;DR: Based on changes in ruminal concentrations of ammonia, synchronous ruminal release of supplemental carbohydrate with pasture N appeared to improve the capture of ruminal N; however, these changes were transient and did not change the N status or performance of dairy cows.
144 citations
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TL;DR: Dietary supplementation with one or a mixture of these functional AA, which include arginine, cysteine, glutamine, leucine, proline, and tryptophan, may be beneficial for ameliorating health problems at various stages of the life cycle and optimizing efficiency of metabolic transformations to enhance muscle growth, milk production, egg and meat quality and athletic performance.
Abstract: Recent years have witnessed the discovery that amino acids (AA) are not only cell signaling molecules but are also regulators of gene expression and the protein phosphorylation cascade. Additionally, AA are key precursors for syntheses of hormones and low-molecular weight nitrogenous substances with each having enormous biological importance. Physiological concentrations of AA and their metabolites (e.g., nitric oxide, polyamines, glutathione, taurine, thyroid hormones, and serotonin) are required for the functions. However, elevated levels of AA and their products (e.g., ammonia, homocysteine, and asymmetric dimethylarginine) are pathogenic factors for neurological disorders, oxidative stress, and cardiovascular disease. Thus, an optimal balance among AA in the diet and circulation is crucial for whole body homeostasis. There is growing recognition that besides their role as building blocks of proteins and polypeptides, some AA regulate key metabolic pathways that are necessary for maintenance, growth, reproduction, and immunity. They are called functional AA, which include arginine, cysteine, glutamine, leucine, proline, and tryptophan. Dietary supplementation with one or a mixture of these AA may be beneficial for (1) ameliorating health problems at various stages of the life cycle (e.g., fetal growth restriction, neonatal morbidity and mortality, weaning-associated intestinal dysfunction and wasting syndrome, obesity, diabetes, cardiovascular disease, the metabolic syndrome, and infertility); (2) optimizing efficiency of metabolic transformations to enhance muscle growth, milk production, egg and meat quality and athletic performance, while preventing excess fat deposition and reducing adiposity. Thus, AA have important functions in both nutrition and health.
2,047 citations
15 Feb 2016
TL;DR: The following table summarizes the nutrient requirements of dairy cattle by type of milk type and type of feed they receive.
Abstract: Nutrient requirements of dairy cattle , Nutrient requirements of dairy cattle , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
1,765 citations
TL;DR: Some of the characteristics of dietary ingredients that should be considered when formulating diets for lactating dairy cows and when allocating feeds to different groups of animals on the farm are discussed.
1,360 citations
TL;DR: The system is based on NDF as the measure of total chemical fiber in feeds and Adjustments for the effectiveness of NDF in maintaining milk fat production and optimizing ruminal fermentation are based on the particle size and inherent characteristics ofNDF that affect chewing activity, ruminal pH, and milkfat production.
1,269 citations
TL;DR: It was concluded that optimum bacterial growth in the rumen occurs when EMPS is 29 g of bacterial N/kg of fermented organic matter, and ENU is 69%, implying that bacteria would require about 1.31 x rumen-available N per unit ofacterial N.
1,144 citations