Biomedical subjects

M R Dentine

Publications and source records attributed to M R Dentine.

29 records · Page 2Linked to original sources

PubMed1991

Serum concentrations of the milk proteins alpha-lactalbumin and beta-lactoglobulin in pregnancy and lactation: correlations with milk and fat yields in dairy cattle.

Serum concentrations of alpha-lactalbumin and beta-lactoglobulin in first pregnancy, parturition, lactation, involution, and second parturition in 37 Holstein cattle were determined and used as an index of mammary status and in predicting milk yield. During first pregnancy, serum alpha-lactalbumin increased in the last 3 mo and reached a peak at parturition (approximately 1100 ng/ml). Changes in alpha-lactalbumin could not be described by a simple exponential equation, whereas changes in serum beta-lactoglobulin were described by a single exponential from second trimester until 4 wk prepartum and reached a peak at parturition (approximately 460 ng/ml). By 2 wk after parturition, alpha-lactalbumin had dropped to approximately 140 ng/ml, and beta-lactoglobulin dropped to approximately 25 ng/ml. In late lactation, alpha-lactalbumin was approximately 70 ng/ml and beta-lactoglobulin approximately 20 ng/ml. Short-term elevations were found after cessation of milking in both alpha-lactalbumin and beta-lactoglobulin in serum. The concentrations of alpha-lactalbumin and beta-lactoglobulin at second parturition were similar to those at first parturition with no differences found between parity. Both alpha-lactalbumin and beta-lactoglobulin in serum were functionally associated with mammary growth and development. In heifers late in pregnancy, both serum concentrations of alpha-lactalbumin and beta-lactoglobulin were positively correlated with mature equivalent milk and fat yields in the subsequent lactation. Serum beta-lactoglobulin concentrations at 16 wk prepartum in heifers were highly correlated with the sum of first and second lactation milk (r = .60) and fat (r = .60) yields. The potential value of using serum beta-lactoglobulin as an index for prescreening of heifers for lactation potential is discussed.

Animals↗

PubMed1990

Estrogen induction of fatty liver in dairy cattle.

Two trials were conducted to determine if estrogen contributes to development of fatty liver in dairy cattle. During trial 1, eight late lactation, nonpregnant cows were assigned to 0 or 15 mg estradiol-17 beta benzoate/d treatment. Days 1 to 3 of the trial were for baseline measurements, and treatments were given from d 4 to 21; on d 20 and 21 animals were fasted. Short-term feed deprivation resulted in increased plasma FFA concentrations and rapid accumulation of triglyceride into liver tissue obtained by biopsy. During starvation, plasma FFA concentration and liver triglyceride content were lower for cows receiving the estradiol-17 beta treatment relative to cows receiving control treatment. Very low density lipoprotein concentration in blood increased dramatically in three of four animals during estradiol-17 beta administration. Because of the decrease in milk production during estradiol-17 beta treatment, it was not known whether this represented a decrease in very low density lipoprotein clearance from blood or reflected a lipotropic response to estradiol-17 beta. Therefore, a second trial was conducted employing nonlactating cows, and control and estradiol-17 beta-treated animals were pair fed. The trial was 33 d with d 1 to 3 for baseline measurements, and treatments were administered from d 4 to 33. All animals were starved from d 19 to 23. Estradiol-17 beta increased hepatic lipid and triglyceride accumulation and plasma very low density lipoprotein concentration during starvation. Plasma FFA concentration was also increased by estradiol-17 beta during this time; therefore, a direct or indirect effect of estrogen on hepatic lipid metabolism could not be delineated.

Animals↗

PubMed1989

Restriction fragment length polymorphisms associated with growth hormone and prolactin genes in Holstein bulls: evidence for a novel growth hormone allele.

Sperm DNA isolated from sons of three extensively used US Holstein bulls was screened for differences associated with the primary gene structure of the bovine growth hormone (bGH) and prolactin (bPrl) genes. Southern blot analysis of DNA digested with 10 restriction enzymes revealed that offspring from two of the three bull families exhibited polymorphisms around the bGH and bPrl genes. Restriction fragment length polymorphisms (RFLPs) around the bGH gene were detected with five enzymes, whereas three enzymes revealed RFLPs around the bPrl gene. At least three structural differences were predicted around the bGH gene. The most common variant hybridization pattern appeared to involve an insertion/deletion located downstream of the conserved 3' EcoRI site. The presence of RFLPs in the genes coding for these pituitary hormones within a familial line may provide the basis for genetic markers associated with lactation and mammary development.

Alleles↗

PubMed1989

Effects of sodium bicarbonate or sodium sesquicarbonate on lactating Holsteins fed a high grain diet.

Fifteen Holstein cows, 35 to 70 d postpartum, were assigned to five 3 x 3 Latin squares. Treatments were: control (60% concentrate, 40% corn silage, DM basis) or control supplemented with either .71% sodium bicarbonate or .65% sodium sesquicarbonate, DM basis. Orthogonal contrasts compared the effect of both buffered diets versus the control diet, and the effect of sodium bicarbonate supplementation vs. sodium sesquicarbonate supplementation. There were no differences among treatments for milk yield (34.9 kg/d), milk fat yield (.99 kg/d), 3.5% FCM (31.1 kg/d), or milk protein concentration (3.15%). There were no treatment effects on total chewing time. Milk fat concentration tended to be greater for cows fed sodium bicarbonate (2.92%) and sodium sesquicarbonate (2.89%) relative to control (2.82%). Relative to control, sodium bicarbonate and sodium sesquicarbonate supplementation increased DM intake (22.0 and 22.7 vs. 21.4 kg/d), digestible DM intake (16.7 and 16.2 vs. 14.8 kg/d), digestible organic matter intake (16.0 and 15.5 vs. 14.3 kg/d); and apparent digestibility of DM (77.3 and 74.8 vs. 73.3%) and NDF (62.6 and 56.5 vs. 54.7%). Relative to sesquicarbonate, bicarbonate supplementation increased apparent digestibilities of CP (82.3 vs. 78.8%) and NDF, and decreased milk protein yield (1.06 vs. 1.11 kg/d). Sesquicarbonate was as effective as bicarbonate in alleviating milk fat depression and increasing intake of digestible organic matter.

Animals↗

PubMed1989

Assessment of lipoprotein activators of skim milk lipoprotein lipase and the relationship between lipoprotein lipase activity and milk fat synthesis.

Bovine plasma and lipoproteins isolated by gel filtration chromatography were examined for their ability to activate skim milk lipoprotein lipase. Addition of equal amounts of protein from either triglyceride-rich lipoprotein, low density lipoprotein, high density lipoprotein or plasma to a lipoprotein lipase assay resulted in 6.0, 2.2, 2.5, or 1.1% hydrolysis of radiolabelled triglyceride emulsion. Lipoprotein lipase activity in skim milk was evaluated as an indicator of mammary lipid secretory capacity. Skim milk lipoprotein lipase activity was significantly lower immediately prepartum as compared with activity immediately postpartum (.2 vs. 5.4% of substrate hydrolyzed). Skim milk lipoprotein lipase was significantly higher during the final 12 d of lactation than in samples obtained 12 d after machine milking was terminated (5.6 vs. less than 1% of substrate hydrolyzed). Although skim milk lipoprotein lipase activity appeared positively related to mammary lipid secretory capacity during the time immediately surrounding initiation and cessation of copious milk production, activity between those periods was not correlated to milk fat percentage, milk fat yield, or stage of lactation.

Animals↗

PubMed1989

Seasonal effects of prepartum and postpartum fat and niacin feeding on lactation performance and lipid metabolism.

Control, prilled fat (5% of ration DM), niacin (12 g/d), or fat and niacin treatments were fed to 39 Holstein cows beginning 17 d prior to expected calving through 15 wk postpartum to determine effects on hepatic lipid content, plasma ketone concentration, and lactation performance. Cows were blocked according to season of calving (cool = November 1 through April 1; warm = April 2 through August 1). Fat supplementation tended to increase milk yield but only for cows that calved in the warm season. Milk composition was not affected by treatments. Fat supplementation did not decrease BW loss in early lactation but increased rate of BW gain af ter 8 wk postpartum. Dry matter intake and glucose, nonesterified fatty acid, and beta-hydroxybutyrate concentrations in plasma were not different among treatments. Fat and niacin supplementation tended to increase hepatic total lipid and triglyceride content. Between 17 d prior to expected calving and 1 to 2 d postpartum, hepatic lipid content increased approximately 2-fold and triglyceride content increased 6- to 10-fold. Hepatic lipid and triglyceride contents were greater postpartum during the warm season than the cool season and were greater at 5 wk than at freshening during the warm season but lower at 5 wk than at freshening during the cool season. The cause of the dramatic increase in hepatic lipid and triglyceride content prepartum is unknown.

Animal Feed↗

PubMed1988

Wet corn gluten feed as a supplement for lactating dairy cattle and growing heifers.

A lactation trial and a heifer growth trial were conducted to evaluate use of wet corn gluten feed by dairy herds. Twelve multiparous and 4 primiparous Holsteins were assigned to 4 x 4 Latin squares blocked according to previous production or parity. Animals received increasing amounts of wet corn gluten feed, up to 36% of ration DM, in place of a dry corn and soybean meal concentrate mixture. Each kilogram of wet corn gluten feed DM replaced .9 kg concentrate DM. Diets were based on ensiled forage with 33% of forage DM from wilted alfalfa silage and the remainder from corn silage. Forage and supplement were fed separately. Milk production, composition, and DM intake were not affected by increased feeding of wet corn gluten feed. Higher producing cows performed well on this feed. Wet corn gluten feed was generally acceptable when fed separately, but two animals refused sizable portions when fed the highest amount. Wet corn gluten feed can be utilized in traditional stall feeding of dairy cattle, and individual feeding should allow better management of this feed resource by limiting the amount offered to cattle that find it unpalatable. Wet corn gluten feed is also an adequate supplement for raising dairy replacements, allowing more rapid utilization of this perishable feed resource by the dairy herd.

Animal Feed↗

PubMed1988

An alternative model for additive and cytoplasmic genetic and maternal effects on lactation.

Results from a recent study that presented evidence suggesting a lack of cytoplasmic inheritance of lactation traits were reexamined using a model that included effects of additive genotype, cytoplasmic genotype, their interaction, and maternal influences. Under this model, equivalent estimates of heritability from daughter-dam and grand-daughter-grand-dam regression that exceed those from paternal half-sib correlation were consistent with the presence of cytoplasmic inheritance. A definitive answer to the question of cytoplasmic inheritance of lactation traits awaits a designed experiment, likely employing transfer of identical nuclei into varying cytoplasmic backgrounds.

Animals↗

PubMed1987

Influence of stage of cycle, corpus luteum location, follicle size, and number of large follicles on estradiol-17 beta concentrations in bovine follicles.

Concentrations of estradiol-17 beta in follicular fluid were correlated to follicular size, stage of estrous cycle, location of corpus luteum, and presence of large follicles. Paired ovaries were obtained from 481 nonpregnant cows at slaughter and follicles were classified as ipsilateral or contralateral to the corpus luteum. Follicular fluid estradiol-17 beta concentrations from 2494 small, 1485 medium, and 396 large follicles were quantified by radioimmunoassay. Stage of estrous cycle was estimated by visual examination of the corpus luteum. Follicles in stage 1 of the estrous cycle (d 1 to 4) had the highest estradiol-17 beta concentration and the smallest mean follicular diameter. Location of follicles relative to the corpus luteum had no influence on estradiol-17 beta concentrations. As follicular size increased, concentration of estradiol-17 beta also increased. The presence of a single large follicle did not affect the concentration of estradiol-17 beta in medium or small follicles. In contrast, if multiple large follicles occurred in the same cow, concentrations of estradiol-17 beta were significantly lower in medium but not small follicles.

Animals↗

PubMed1984

Associations of subjective udder edema scores and descriptive trait codes for udder types.

Edema severity was scored by herd personnel in six North Carolina Holstein herds from 1 (none) to 5 (extremely severe). Cows (2612) were scored at calving and 1 and 2 wk postpartum. Total score was calculated as the sum of these three scores. Official Holstein-Friesian classification descriptive udder trait codes were available on a subset of the cows. All statistical analyses were within lactation and included adjustments for herd-year and age as well as classifier and stage of lactation where appropriate. Correlations between corresponding edema scores for first and second lactations were .18, .18, .19, and .20 for scores at calving, 1 wk, 2 wk, and for total score. Stepwise regression procedures showed that udder support codes were associated with a larger amount of variation of edema scores than for any other single mammary trait code. Fore and rear udder codes also were associated with significant variation of edema scores in some analyses. Prediction models showed edema was a significant predictor of subsequent udder support codes, although udder trait codes were not significant predictors of subsequent edema severity. It appeared that severe edema may be one of the causes of pendulous udders.

Animals↗

PubMed1983

Variation of edema scores from herd-year, age, calving month, and sire.

Edema was scored by herd personnel in six Holstein herds in North Carolina. Scores ranged from 1 (none) to 5 (extremely severe) at calving and at 1 and 2 wk postpartum. Mean scores and standard deviations were 2.91 +/- .71 at calving, 2.12 +/- .71 at 1 wk, and 1.54 +/- .64 at 2 wk. Total score, the sum of the three ratings for each calving, averaged 6.57 +/- 1.89. Scores differed by herd-year and lactation but not by month of calving. Heritabilities within first, second, and grouped later (greater than or equal to 3) lactations were estimated by paternal half-sister covariance analyses from two subsets of the data. The first data set included sires with 5 or more daughters; the second, sires with 10 or more daughters. Heritabilities averaged .13 for first lactations, .10 for second lactations, and .12 for later lactations. When adjusted to underlying normal distribution, heritabilities were increased. These heritabilities suggest that progeny tests based on 50 or more daughters should identify bulls transmitting more persistent edema. The desirability of such progeny tests depends on the relative importance and economic impact of reduced edema severity in the dairy cattle population.

Age Factors↗