Regulation of Periparturient Milk Composition in Jersey Cattle

The composition of milk from dairy cows varies more in the colostral period than in other periods of lactation. The objective of this study was to determine which factors influence milk composition of Jersey cows during the colostral period. Composite milk samples were collected from 21 lactating Jersey cows of the Iowa State University Teaching Herd between February and July at 0, 12, 24, 30, 38, 46, 54, 62, 80, and 88 hours postpartum. The milk samples were analyzed for total fat, lactose, and protein content by infrared spectroscopy, for total protein nitrogen, non-casein nitrogen, and non-protein nitrogen content by Kjeldahl analyses, and for αS1–casein, β-casein, κ-casein, αS2-casein, α-lactalbumin, and β–lactoglobulin concentrations by reversed-phase HPLC. Milk composition changed during the first 4 days after parturition and was influenced by calving season, length of gestation, and parity; and all had significant interactions with time postpartum (all P \u3c 0.01). Colostrum matured to normal milk in the first two days after parturition. The maturation of colostrum was associated with an increase in lactose content and a decrease in protein content, in particular of whey proteins other than α–lactalbumin. The colostrum of cows that calved between February and April had a lower lactose and a greater protein content, in particular of whey proteins other than α–lactalbumin and β–lactoglobulin, than did colostrum of cows that calved in May and June. The colostrum of multiparous cows was higher in protein content than was the colostrum of heifers because of higher concentrations of whey proteins. During the colostral period, milk of cows that calved before the predicted calving date had greater protein concentrations than did milk from cows that calved at or after the predicted calving date, which was the result of higher concentrations of whey proteins other than α–lactalbumin and β–lactoglobulin. We conclude that time postpartum, calving season, length of gestation, and parity affect the composition of milk in the early secretory period in lactating Jersey cows

Redesigning Pork by Type and Amount of Dietary Fat for Bet- ter Human Nutrition

An experiment to modify pork by supplementa- tion of dietary lipids yielded the following conclusions: 1) Supplementation of pig diets with high levels of lipids did improve feed conversion without affecting other growth performance characteristics. 2) Feeding of choice white grease increased the content of monounsaturated fatty acids in skeletal muscle and adipose tissues of pigs. 3) Feeding soybean oil, increased the content of polyunsatu- rated fatty acids in skeletal muscle and adipose tissues of pigs

Parturition Invokes Changes in Peripheral Blood Mononuclear Cell Populations in Holstein Dairy Cows Naturally Infected with Mycobacterium Avium Subsp. Paratuberculosis

Twenty-one multiparous and two primiparous Holstein cows were grouped according to infection status with Mycobacterium avium subsp. paratuberculosis (MAP), the causative microorganism for Johne’s disease (JD). The effect of parturition and infection on the percentages of CD4 + , CD8 + , and T-cells, B-cells, and monocytes in the peripheral blood were monitored. The data suggest that changes in the percentages of lymphocyte subsets and monocytes are modulated by both infection status and the periparturient period

Osteopontin Expression in Periparturient Dairy Cows Naturally Infected with Mycobacterium Avium Subsp. Paratuberculosis

Twenty-five multiparous Holstein cows were grouped according to infection status with Mycobacterium avium subsp. paratuberculosis (MAP), the causative microorganism of Johne’s disease (JD). Osteopontin (Opn) was characterized at both the level of gene and protein expression. Results of this study indicate that in dairy cows, expression of Opn is modulated by natural infection with MAP and by the periparturient period

Changes in Milk Protein and Amino Acid Composition of Dairy Cows in Response to Fatty Liver and Intravenous Glucagon

Intravenous glucagon cures fatty liver by improving glucose bioavailability in early lactation. Amino acids, which would be otherwise used for milk protein synthesis, are metabolized to glucose. The objective of this study was to examine whether intravenous glucagon and fatty liver change milk protein and amino acid composition in dairy cows. Multiparous Holstein cows (n=25) were designated as either normal or susceptible to fatty liver and ketosis as based on the ratio of liver triacylglycerol to glycogen being smaller or greater than 2.0 at d 6 postpartum. Cows susceptible to fatty liver were subjected for 3 weeks to a protocol consisting of feed restriction and dietary 1,3- butanediol beginning at d 14 postpartum, which induced fatty liver and ketosis. Normal cows and cows with fatty liver were infused with glucagon for 14 d at 0 or 10 mg/d beginning at d 21 postpartum. Composite milk samples were obtained at d 20, 22, 34, and 36 postpartum and analyzed for milk protein and amino acid composition. Fatty liver decreased milk yield but had little effect on milk protein and amino acid composition except for increasing the proportion of glycosylated κ-casein. Intravenous glucagon decreased total milk protein concentrations and the proportion of α–lactalbumin and increased the proportion of glycosylated κ-casein, total κ-casein, and αS2-casein. Intravenous glucagon had little effect on milk amino acid composition. Our results suggest that milk protein and amino acid composition are under tight concomitant hormonal control and are affected little by changes in amino acid availability and/or insulin to glucagon ratio

Milk Protein Genotypes Explain Variation of Milk Protein Composition

The data demonstrate that cows with the genotypes κ- casein BB and β-lactoglobulin BB produce milk with a protein composition that is favorable for increased cheese yield. For proportions of αS1-casein, κ-casein, and β-lactoglobulin in total milk protein, κ-casein and β-lactoglobulin genotypes explained more than 50 and 25% of the heritability and repeatability estimates, respectively, and more than 14% of the phenotypic variance. Diet had only a minimal effect on milk protein composition. In conclusion, increasing cheese yield through modification of milk protein composition can be achieved most rapidly by selection for cows with κ-casein BB and β-lactoglobulin BB genotypes

Nutrient Regulation of Plasma Ghrelin Concentration in Lean and Overweight Female Humans

Investigating the role of appetite-related hormones on energy balance and body composition when varying diets are consumed could provide insight into the etiology of obesity. Eight female subjects, ages 20–30, were used in this study: four normal subjects with body mass index (BMI) of 19–24 and four overweight/obese subjects with of BMI of 27–30. Each subject received both treatments by a crossover design. Two normal and two overweight subjects were assigned to the Atkins’ diet. The Atkins’ diet contained 10% of energy as carbohydrate, 45% of energy as protein, and 45% of energy as lipid. The remaining two normal and two overweight subjects were assigned to the AHA diet that contained 63% of energy as carbohydrate, 12% of energy as protein, and 25% of energy as lipid. Each diet was fed for 14 days, and then subjects were switched to the other diet. We hypothesized that subjects consuming the Atkins’ diet would have lower plasma ghrelin concentrations than subjects consuming the AHA diet. On days 6 and 20, blood was taken at one hour before and after the noon meal. Blood was taken every hour from 7 am to 9 pm on days 13 and 27 of the study. On days 14 and 28, subjects were fasted from 7 am to 12 pm and fed their meal at noon. Two blood samples were taken on days 14 and 28 at 11 am and one hour after the meal. All plasma samples were analyzed for ghrelin. Normal weight women consuming the Atkins diet had lower fasting ghrelin concentrations than did women consuming the AHA diet (p=0.0141). Ghrelin concentrations in overweight women were not significantly different (p=0.8076). These results indicate a relationship of appetite-related hormones with respect to diet composition

Effects of Dietary Macronutrients on Appetite-Related Hormones in Blood on Body Composition of Lean and Obese Rats

Investigating the role of appetite-related hormones on energy balance and body composition when varying diets are consumed could provide insight into the etiology of obesity. Fifty-three adult male Sprague Dawley and 30 adult male Zucker Fatty rats were assigned randomly to one of five diets: Control, 75% control, American Heart Association (AHA), Atkins, or high fat (HF). Diets were fed for five weeks. Weekly plasma samples were collected and analyzed for ghrelin, leptin, insulin, and adiponectin. Terminal plasma samples were analyzed for ghrelin, leptin, insulin, glucagon, oxyntomodulin, adiponectin, and blood metabolites. Our results indicate that macronutrient composition of the diet influences appetite-related hormones differently in genetically divergent rats. For example, glucagon concentration was higher in obese rats fed the Atkins diet in comparison to obese rats fed the HF and 75% control diets (P\u3c0.05) and tended to be higher in obese rats fed the Atkins diet in comparison with rats fed the AHA and control diets (0.0

Early Inflammation Disorder in Neonatal Calves

In the present study, 30 Holstein calves were acquired at birth and were randomly subjected to one of six treatments. One treatment group was colostrum deprived (CD) and five other treatment groups were fed colostrum replacer (CR). Of the five CR groups, one group was not further supplemented (CR), one received vitamin A (CR-A), one received vitamin D (CR-D), one received vitamin E (CR-E), and one received vitamins A, D, and E (CR-ADE). Additionally, all calves were inoculated with Mycobacterium avium, subsp. paratuberculosis on d 1 and d 3 of age. One d after birth, CD calves exhibited lower IgG1, haptoglobin, and serum amyloid A concentrations in serum compared with the other five CR groups. These findings point to an endogenous early inflammation disorder in calves that are not fed colostrum

Texture of Butters Made from Milks Differing in Indices of Atherogenicity

The current study examined whether the phenotypic variation in milk fatty acid composition among cows fed the same diet was sufficient to produce butter with different textural properties. Butter samples from cows with a more unsaturated milk fatty acid composition had a lower index of atherogenicity and were more spreadable, softer, and less adhesive than were butter samples from cows with a more saturated milk fatty acid composition. Thus, selection of cows for milk fatty acid composition short-term by segregation and long-term by breeding programs can be used to produce butter that is more healthful and has a more favorable texture