Performance, metabolic, and endocrine responses of periparturient Holstein cows fed 3 sources of fat.

The objective of this study was to examine the effect of feeding diets containing fat supplements enriched in either saturated fatty acids (n = 10), Ca salts of trans-octadecenoic fatty acids (tFA, n = 10) or Ca salts of safflower oil fatty acids (SFL, high in linoleic acid, n = 9) on performance, metabolic, and endocrine responses of periparturient Holstein cows. Dietary treatments were initiated at approximately 28 d before calculated calving dates and continued through 49 d postpartum. Blood samples for metabolite and hormone analyses were collected weekly beginning 1 wk before estimated calving date through 7 wk postpartum. Incorporation of tFA or SFL into the peripartum diet had no detectable effects on body weight or body condition score. Cows fed the SFL-enriched diet produced less milk fat and established a positive energy balance sooner after calving than those fed the tFA supplement. Analysis for individual fatty acids resulted in increased concentrations of trans 18:1 fatty acid and conjugated linoleic acid isomers in milk fat from cows supplemented with SFL. Across weeks, the average nonesterified fatty acids concentration in plasma was lower in cows fed the SFL-enriched diet than in those consuming the tFA-supplemented diet. Mean concentrations of plasma glucose, insulin-like growth factor-I, and progesterone were greater in cows fed the SFL-enriched diet compared with those fed the saturated fatty acid-supplemented diet. Feeding fat supplements that can suppress milk fat production during the early postpartum period may help minimize negative energy balance, reduce adipose tissue mobilization, and improve circulating concentrations of insulin-like growth factor-I and progesterone. Whether the SFL supplement would have similar effects without a decrease in milk fat production remains to be determined and warrants further investigation.

Plasma prostaglandin and cytokine concentrations in periparturient Holstein cows fed diets enriched in saturated or trans fatty acids.

After parturition, immune functions such as lymphocyte response to mitogens and production of antibodies are depressed in dairy cows. Dietary regimens that improve the immune function of dairy cows after calving may improve uterine health and lead to earlier breeding after parturition. The objective of this study was to examine the effect of feeding a calcium salt of trans isomers of fatty acids (tFA) to periparturient Holstein cows on plasma biomarkers of inflammation. Dietary treatments were initiated approximately 28 d before expected calving date and continued through d 21 postpartum. Prepartum and postpartum diets were formulated to be isolipidic, containing 1.5% saturated fats (n = 15) or 1.8% tFA (n = 15). Multiparous cows were heavier at calving (+32%) and produced more milk (+17%) than primiparous cows. Periparturient tFA supplementation increased plasma PGF(2alpha) metabolite concentration in multiparous cows, but not in primiparous cows. Concentrations of prostaglandin E(2), tumor necrosis factor-alpha, and interleukin-4 in plasma did not differ between diets and parities. Results raise the possibility that peripartum tFA supplementation may affect uterine health and reproductive efficiency of early lactation dairy cows through alteration of peripheral PGF(2alpha) concentration.

Effects of dietary n-6:n-3 fatty acid ratio on feed intake, digestibility, and fatty acid profiles of the ruminal contents, liver, and muscle of growing lambs.

This study investigated the effect of modifying the n-6:n-3 fatty acid ratio (FAR) of diets using linseed, soybean, and cottonseed oils on apparent digestibility, ruminal fermentation characteristics, growth performance, key circulating hormones, and the fatty acid profile of ruminal digesta, liver, and fore-shank muscle of growing lambs fed a high concentrate diet. Forty individually housed Katadhin Dorper lambs (average of 20.0 kg of BW) were fed Bermudagrass hay in ad libitum amounts and concentrates at 3.7% of BW daily. The concentrate contained 68.9% corn, 23.8% soybean meal, 3.3% limestone, and 4.0% oil supplements (DM basis). The treatments consisted of dietary n-6:n-3 FAR of 2.3:1, 8.8:1, 12.8:1, and 15.6:1. After feeding for 35 d in metabolism crates, lambs were slaughtered 15 h after feeding, and samples of ruminal digesta, blood, liver, and foreshank tissue were collected. Increasing dietary n-6:n-3 FAR did not affect the intake of DM nor the apparent digestibility of DM, ether extract, NDF, or ADF, but did increase apparent digestibility of CP (linear, P < 0.05). Concentrations of ruminal butyrate increased linearly (P < 0.05) with increasing dietary n-6:n-3 FAR, whereas the valerate concentration decreased linearly (P < 0.001). Concentrations of plasma insulin and IGF-I were not affected by dietary n-6:n-3 FAR. Concentrations of C18:3n-3 increased linearly (P < 0.001), whereas that of C18:2n-6 decreased linearly (P < 0.001) in ruminal digesta with decreasing dietary n-6:n-3 FAR. Concentrations of transisomers of fatty acids in ruminal digesta did not change. Proportions of C18:0 in liver and foreshank muscle were unchanged by diet. The proportion of trans11 C18:1 and cis-9 trans11 CLA decreased (P < 0.05) in liver but increased (P < 0.05) in foreshank muscle as dietary n-6:n-3 FAR decreased. Proportions of all measured n-3 fatty acids were greater in liver when diets contained more C18:3n-3 from linseed oil. By decreasing the dietary n-6:n-3 FAR, the proportions of n-6 fatty acids in foreshank muscle decreased dramatically; specifically, C18:2n-6 decreased linearly (P < 0.001) from 28.0 to 16.5% and C20:4n-6 decreased linearly (P < 0.001) from 14.7 to 8.6%. Although feeding a diet that contained more n-3 fatty acids increased the n-3 fatty acid concentration of muscle, the ratio of PUFA to SFA was decreased.

Effects of biotin supplementation on peripartum performance and metabolites of Holstein cows.

Fifty-two multiparous Holstein cows were randomly assigned to receive 0 or 20 mg of biotin/d starting at an average of 16 d prepartum and then switched to 0 or 30 mg of biotin/d from calving through 70 d postpartum to determine whether supplemental biotin would affect cow performance, hepatic lipidosis, and plasma metabolites. Mean concentration of biotin in plasma sampled weekly was greater in cows fed biotin (4.3 vs. 9.4 nmol/L). Postpartum dry matter intake as a percentage of body weight (3.9% vs. 4.0%), milk production (35.8 vs. 34.8 kg/d), and milk fat concentrations (3.59% vs. 3.69%) were similar between treatment groups. Milk from biotin-supplemented cows tended to have a greater concentration of protein (2.73% vs. 2.83%). Concentrations of plasma nonesterified fatty acids were lower at wk 2 (652 vs. 413 microEq/mL) and 4 (381 vs. 196 microEq/mL) postpartum in cows fed supplemental biotin. However, mean plasma concentrations of beta-hydroxybutyric acid were not affected by biotin supplementation. Mean concentration of plasma glucose was greater for lactating cows fed supplemental biotin (63.4 vs. 66.6 mg/dL). Biopsies of liver were taken at 2, 16, and 30 d postpartum. The triacylglycerol concentration in liver (wet basis) tended to decrease at a faster rate after d 2 postpartum with biotin supplementation compared with control cows. The potential mechanisms that link improved glucose status and decreased lipid mobilization in cows supplemented with biotin warrant further investigation.

Production and metabolic responses of periparturient Holstein cows to dietary conjugated linoleic acid and trans-octadecenoic acids.

Thirty-eight multiparous Holstein cows were utilized in a completely randomized design to examine the effect of feeding calcium salts of conjugated linoleic acid (CLA) and trans-octadecenoic acids (trans-C18:1) on animal performance and lipid and glucose metabolism during the transition to lactation. Dietary treatments were initiated approximately 28 d prior to expected calving dates and continued through d 49 postpartum. Prepartum treatments consisted of 1) a basal diet (Control), 2) basal diet + 150 g/d of CLA mix (CLA), and 3) basal diet + 150 g/d of trans-C18:1 mix (TRANS). Amounts of calcium salts of CLA and trans-C18:1 mixes were adjusted to 225 g/d during the 49-d postpartum treatment period. All diets were offered as a total mixed ration. Prepartum fat supplementation had no detectable effects on dry matter intake, body weight, or body condition score. After parturition, cows in the TRANS group consumed less dry matter at wk 4, 5, and 6 of lactation than did cows in the control group. Cows fed the trans-C18:1 supplement were in a more severe negative energy balance than those fed the control diet at 1 wk of lactation. Periparturient fat supplementation had no detectable effects on milk yield during wk 1 to 7 of lactation. Milk fat was not affected during wk 1 to 4, but was reduced after wk 4 of lactation by dietary CLA. Feeding calcium salts of CLA decreased short- to medium-chain fatty acid (C4 to C14) concentrations and increased both linoleic and linolenic acid concentrations in milk fat. Concentrations of nonesterified fatty acids and beta-hydroxybutyric acid in blood were greater in cows fed the CLA-supplemented diet than in those fed the control diet at 1 wk of lactation. In spite of small numerical tendencies, hepatic lipid and triacylglycerol concentrations did not vary significantly among dietary treatments. Periparturient fat supplementation had no detectable effects on plasma glucose and insulin concentrations. Steady-state concentrations of hepatic mRNA encoding pyruvate carboxylase and phosphoenolpyruvate carboxykinase were greater for the TRANS treatment group than the control and CLA groups. Results indicate that dietary CLA and trans-C18:1 fatty acids may affect lipid and glucose metabolism in early postpartum Holstein cows through distinct mechanisms.

Dietary conjugated linoleic acid alters hepatic lipid content and fatty acid composition in broiler chickens.

We examined the effect of dietary conjugated linoleic acid (CLA) on growth performance and liver composition in broiler chickens. Day-old male broiler chicks were assigned to receive a diet supplemented with corn oil (5%; n = 48) or CLA (5%; n = 48) for 21 d. Broilers fed CLA weighed less and grew at slower rates than broilers fed corn oil. Feed intake and feed conversion were higher for the corn-oil group than for the CLA dietary group. Hepatic lipid and triacylglycerol concentrations were significantly reduced by dietary CLA. The proportions of saturated fatty acids (SFA) in liver lipids increased, whereas those of monounsaturated fatty acids (MUFA) decreased with CLA supplementation. Although the total concentration of polyunsaturated fatty acids (PUFA) did not change with dietary treatment, the concentration of linoleic acid as a percentage of total methylated fatty acids decreased, and that of linolenic add increased in broilers fed CLA. The concentration of CLA isomers in liver lipids increased substantially with CLA feeding. The relative proportion of the c9,t11 CLA isomer in hepatic lipids was much higher than that of the t10,c12 or t9,t11 CLA isomers. These studies provide evidence that feeding CLA to broilers results in substantial reduction in liver fat accumulation and promotes CLA incorporation into hepatic lipid pools.

Paracrine inducers of uterine endometrial spermidine/spermine N1-acetyltransferase gene expression during early pregnancy in the pig.

The endogenous factors that underlie the transient induction of the gene encoding spermidine/spermine N1-acetyltransferase (SSAT), the rate-limiting enzyme in cellular polyamine catabolism, in pig uterine endometrium during periimplantation are not known. The present study examined a number of peptide growth factors and regulatory molecules that are present within the uterine environment at early pregnancy, coincident with maximal SSAT gene expression, for their ability to manifest endogenous SSAT gene-inducing activity. Basal SSAT expression in luminal epithelial cells was higher (p < 0. 01) than that for glandular epithelial (GE) or stromal (ST) cells. Recombinant human insulin-like growth factor-I (IGF-I; 50 ng/ml) had no effect on steady-state SSAT mRNA levels, but it increased mitogenesis in all three cell types. In contrast, IGF-I caused a marked induction (p < 0.01) of SSAT mRNA levels in the human endometrial carcinoma cell line Hec-1-A. Uterine explants incubated with interleukin-6, transforming growth factor alpha, epidermal growth factor (each at 1, 10, and 100 ng/ml), retinoic acid and retinol (each at 0.01, 0.1, and 1 microM), and estradiol-17beta (10 nM) had SSAT mRNA levels similar to controls. By contrast, leukemia inhibitory factor (LIF; at 10 and 100 ng/ml) caused a modest, but significant (p < 0.05), increase in SSAT mRNA levels over those of untreated explants. This effect of LIF, however, did not approach the level of induction observed in GE or ST cells after addition of medium conditioned by Day 12 or 17 porcine conceptuses and in endometrial explants supplemented with medium conditioned by Day 21 porcine conceptuses or a continuous cell line (Jag-1) derived from Day 14 porcine trophoblast. We suggest that transient induction of endometrial SSAT gene expression at implantation is mediated by the functional interactions of specific conceptus-derived regulatory factors, distinct from estrogen, with endometrial-derived factor(s) such as LIF. These complex interactions are probably requisite for the transient, yet dramatic, induction of SSAT gene expression and may be critical for successful implantation.

Endocrine and ovarian responses associated with the first-wave dominant follicle in cattle.

To examine endocrine and biochemical differences between dominant and subordinate follicles and how the dominant follicle affects the hypothalamic-pituitary-ovarian axis in Holstein cows, the ovary bearing the dominant follicle was unilaterally removed on Day 5 (n = 8), 8 (n = 8), or 12 (n = 8) of synchronized estrous cycles. Follicular development was followed daily by ultrasonography from the day of detected estrus (Day 0) until 5 days after ovariectomy. Aromatase activity and steroid concentrations in first-wave dominant and subordinate follicles were measured. Intact dominant and subordinate follicles were cultured in 4 ml Minimum Essential Medium supplemented with 100 microCi 3H-leucine to evaluate de novo protein synthesis. Five days after unilateral ovariectomy, cows were resynchronized and the experiment was repeated. Follicular growth was characterized by the development of single large dominant follicles, which was associated with suppression of other follicles. Concentrations of estradiol-17 beta (E2) in follicular fluid and aromatase activity of follicular walls were higher in dominant follicles (438.9 +/- 45.5 ng/ml; 875.4 +/- 68.2 pg E2/follicle) compared to subordinate follicles (40.6 +/- 69.4 ng/ml; 99.4 +/- 104.2 pg E2/follicle). Aromatase activity in first-wave dominant follicles was higher at Days 5 (1147.1 +/- 118.1 pg E2/follicle) and 8 (1028.2 +/- 118.1 pg E2/follicle) compared to Day 12 (450.7 +/- 118.1 pg E2/follicle). Concentrations of E2 and androstenedione in first-wave dominant follicles were higher at Day 5 (983.2 +/- 78.2 and 89.5 +/- 15.7 ng/ml) compared to Days 8 (225.1 +/- 78.6 and 5.9 +/- 14.8 ng/ml) and 12 (108.5 +/- 78.6 and 13.0 +/- 14.8 ng/ml). Concentrations of progesterone in subordinate follicles increased linearly between Days 5 and 12 of the estrous cycle. Plasma concentrations of FSH increased from 17.9 +/- 1.4 to 32.5 +/- 1.4 ng/ml between 0 and 32 h following unilateral removal of the ovary with the first-wave dominant follicle. Increases in plasma FSH were associated with increased numbers of class 1 (3-4 mm) follicles in cows that were ovariectomized at Day 5 or 8 of the cycle. Unilateral ovariectomy had no effects on plasma concentrations of LH when a CL was present on the remaining ovary. First-wave dominant follicles incorporated more 3H-leucine into macromolecules and secreted high (90,000-120,000) and low (20,000-23,000) molecular weight proteins that were not as evident for subordinate follicles at Days 8 and 12.(ABSTRACT TRUNCATED AT 400 WORDS)

Factors influencing passive transfer in dairy calves.

Records from 2105 calves born over 2 yr on a large dairy in a subtropical climate were examined to delineate factors that influence passive transfer of colostral immunoglobulins and the effect of passive transfer of immunoglobulin on calf mortality. Seasonal effects on immunoglobulin absorption were detected with highest serum total protein occurring in February and March. Lower total protein concentrations were associated with elevated environmental temperatures in the summer months. Maternal antibody was highest in calves from second parity cows; and dystocia appeared to decrease the amount of immunoglobulin absorbed by the neonatal calf. Calves that died of infectious disease during the first 14 wk of life had significantly lower serum total protein concentrations than those that lived. Heritability of serum protein concentration in calves was .02 +/- .03.