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Biomedical subjects

J K Drackley

Publications and source records attributed to J K Drackley.

At least 19 recordsLinked to original sources
PubMed2006

Growth and body composition of dairy calves fed milk replacers containing different amounts of protein at two feeding rates.

Previous research has demonstrated that increasing the CP concentration from 16 to 26% in milk replacers fed to male preruminant dairy calves at 1.5% of BW (DM basis) daily resulted in increased ADG, G:F, and deposition of lean tissue. However, the effects of dietary CP would be expected to vary depending on ME intake. Here, male Holstein calves < 1 wk old were used to determine the effects of feeding rate and CP concentration of isocaloric, whey protein-based milk replacers on growth and body composition. After a 2-wk standardization period, calves were assigned randomly to an initial baseline group or to treatments in a 2 x 4 factorial arrangement of feeding rate (1.25 or 1.75% of BW daily, DM basis) and milk replacer CP concentration (14, 18, 22, or 26% of DM). No starter was offered, but calves had free access to water. After a 5-wk feeding period, calves were slaughtered and body composition was determined. Increasing the feeding rate increased (P < 0.05) ADG, G:F, empty-body gains of chemical components and energy, the percentage of fat in empty BW gain and in the final empty body, and concentrations of IGF-I and insulin in plasma. Increasing the feeding rate decreased (P < 0.01) percentages of water and protein in the empty body and decreased urea N in plasma. Increasing dietary CP concentration linearly increased (P < 0.05) ADG, body length, heart girth, and gains of water and protein but linearly decreased (P < 0.05) fat gain. As dietary CP increased, fat content in empty body gain decreased, and water and protein increased. Increasing CP concentration increased (quadratic, P < 0.02) G:F, with greatest efficiencies for calves fed 22% CP. Gross energetic efficiency (retained energy:intake energy) was greater (P < 0.05) for calves fed at 1.75% of BW daily. Efficiency of dietary protein use for protein gain was greater for calves fed at 1.75% of BW daily but was not affected by dietary CP. The ratio of protein gain to apparently digestible protein intake above maintenance decreased as dietary CP increased. Interactions (P < 0.05) of feeding rate and CP concentration for gains of water and protein indicated that when dietary CP was 26% the ME supply limited protein use by calves fed at 1.25% of BW daily. Body composition of preruminant calves can be markedly altered by manipulating the protein to energy ratio in milk replacers. These dietary effects on body composition and growth are not predicted by current NRC standards.

Animal Feed↗
PubMed2006

Lipid metabolite profiles and milk production for Holstein and Jersey cows fed rumen-protected choline during the periparturient period.

Choline is important for assembly of very low density lipoproteins to export triglyceride from liver; however, studies to assess the effect of rumen-protected choline (RPC) supplementation on blood lipid metabolites in periparturient dairy cows have not been conducted. Thirty-two multiparous Holstein and 10 multiparous Jersey cows were randomly assigned to control or RPC treatments. A close-up diet was fed from approximately 3 wk before parturition through parturition, followed by a lactation diet from parturition through 49 d postpartum. For RPC, diets were top-dressed once daily with 60 g of a RPC product (25% choline as choline chloride) from 21 d before expected parturition through 21 d postpartum. Treatment did not affect dry matter intake either prepartum (12.0 vs. 12.1 kg/d for RPC and control, respectively) or during the first 3 wk postpartum (14.8 vs. 15.7 kg/d, respectively). Daily yields of 3.5% fat-corrected milk (39.4 vs. 37.4 kg/d), fat (1.46 vs. 1.38 kg/d), and protein (1.09 vs. 1.05 kg/d) did not differ statistically by treatment (RPC vs. control, respectively). Jersey cows in the control group had lower concentrations of nonesterified fatty acids and beta-hydroxybutyrate in plasma during d 1 to 10 postpartum than did other breed and treatment combinations. Cows fed RPC tended to have greater serum triglycerides prepartum (17.0 vs. 14.7 mg/dL) and lower plasma phospholipid at parturition (65.2 vs. 78.1 mg/dL) than control cows. Treatment did not affect cholesterol and phospholipid at other time points, but concentrations followed patterns of dry matter intake pre- and postpartum. Cows were in moderate body condition score (mean = 3.3) at the start of the study and did not lose excessive condition by 3 wk postpartum (mean body condition score loss = 0.5); therefore, cows might not have been at great risk for hepatic lipid accumulation. Additionally, calculated Met balance was negative postpartum; supplemental RPC might not have spared enough Met to produce a physiological benefit. More research is needed to determine how choline affects prevention or alleviation of fatty liver syndrome and to confirm potential differences between Holstein and Jersey cows.

3-Hydroxybutyric Acid↗
PubMed2006

Major advances in fundamental dairy cattle nutrition.

Fundamental nutrition seeks to describe the complex biochemical reactions involved in assimilation and processing of nutrients by various tissues and organs, and to quantify nutrient movement (flux) through those processes. Over the last 25 yr, considerable progress has been made in increasing our understanding of metabolism in dairy cattle. Major advances have been made at all levels of biological organization, including the whole animal, organ systems, tissues, cells, and molecules. At the whole-animal level, progress has been made in delineating metabolism during late pregnancy and the transition to lactation, as well as in whole-body use of energy-yielding substrates and amino acids for growth in young calves. An explosion of research using multicatheterization techniques has led to better quantitative descriptions of nutrient use by tissues of the portal-drained viscera (digestive tract, pancreas, and associated adipose tissues) and liver. Isolated tissue preparations have provided important information on the interrelationships among glucose, fatty acid, and amino acid metabolism in liver, adipose tissue, and mammary gland, as well as the regulation of these pathways during different physiological states. Finally, the last 25 yr has witnessed the birth of "molecular biology" approaches to understanding fundamental nutrition. Although measurements of mRNA abundance for proteins of interest already have provided new insights into regulation of metabolism, the next 25 yr will likely see remarkable advances as these techniques continue to be applied to problems of dairy cattle biology. Integration of the "omics" technologies (functional genomics, proteomics, and metabolomics) with measurements of tissue metabolism obtained by other methods is a particularly exciting prospect for the future. The result should be improved animal health and well being, more efficient dairy production, and better models to predict nutritional requirements and provide rations to meet those requirements.

Absorption↗
PubMed2006

Supplementation of 1% L-glutamine to milk replacer does not overcome the growth depression in calves caused by soy protein concentrate.

Glutamine, an important fuel and biosynthetic precursor in intestinal epithelial cells, helps maintain intestinal integrity and function when supplemented to the diet of many species. The hypothesis tested here was that glutamine supplementation would overcome the decreased average daily gain (ADG) and altered intestinal morphology caused by milk replacer containing soy protein concentrate (SPC). Holstein calves (9 male and 1 freemartin female per treatment) were assigned to diets of 1) all-milk-protein (from whey proteins) milk replacer, 2) milk replacer with 60% milk protein replacement from SPC, and 3) SPC milk replacer as in diet 2 plus 1% (dry basis) l-glutamine. Milk replacers were reconstituted to 12.5% solids and were fed at 10% of body weight from d 3 to 10 of age, and at 12% of body weight (adjusted weekly) from d 10 through 4 wk of age. No dry feed (starter) was fed, but water was freely available. Glutamine was added at each feeding to reconstituted milk replacer. Five calves from each treatment were slaughtered at the end of wk 4 for measurements of intestinal morphology. The ADG was greater for calves fed the all-milk control than for those fed SPC; glutamine did not improve ADG (0.344, 0.281, and 0.282 kg/d for diets 1 to 3, respectively). Intake of protein was adequate for all groups and did not explain the lower growth for calves fed SPC. Villus height and crypt depth did not differ among treatments in the duodenum. In the jejunum, villus height (713, 506, and 464 mum, for diets 1 to 3, respectively) and crypt depth (300, 209, and 229 mum, respectively) were greater for calves fed all milk protein than for either SPC group. In the ileum, villus height was greater for calves fed all milk than for either soy group (532, 458, and 456 mum), whereas crypt depth tended to be greater (352, 301, and 383 mum for diets 1 to 3, respectively), and the villus to crypt ratio was lower for calves supplemented with glutamine than for those fed SPC alone. Urea N concentration in plasma was greater for calves supplemented with glutamine than for those fed SPC alone, indicating that glutamine was at least partially catabolized. Supplemental l-glutamine did not improve growth or intestinal morphology of calves fed milk replacer containing SPC.

Animals↗
PubMed2006

Prepartal plane of nutrition, regardless of dietary energy source, affects periparturient metabolism and dry matter intake in Holstein cows.

Previous research in our laboratory showed that dietary fat supplementation during the dry period was associated with decreased peripartum hepatic lipid accumulation. However, fat supplementation decreased dry matter (DM) intake and thereby confounded results. Consequently, 47 Holstein cows with body condition scores (BCS) < or = 3.5 at dry-off were used to determine whether source or amount of energy fed to dry cows was responsible for the decreased hepatic lipid content. Moderate grain- or fat-supplemented diets [1.50 Mcal of net energy for lactation (NE(L))/kg] were fed from dry-off (60 d before expected parturition) to calving at either ad libitum (160% of NE(L) requirement) or restricted (80% of NE(L) requirement) intakes. Postpartum, cows were fed a single lactation diet for ad libitum intake and performance was measured for 105 d. Prepartum intakes of DM and NE(L) were significantly lower for feed-restricted cows as designed. During the first 21 d postpartum, previously restricted cows had higher intakes of DM and NE(L). Body weights and BCS were lower prepartum for restricted cows but groups converged to similar nadirs postpartum. Restricted-fed cows had lower concentrations of glucose and insulin and increased concentrations of NEFA in plasma during the dry period. Peripartum NEFA rose markedly for all treatments but were higher postpartum for cows previously fed ad libitum. Plasma concentrations of NEFA and BHBA remained lower in cows restricted-during the dry period. Postpartum concentrations of total lipid and triglyceride in liver were lower in cows previously feed-restricted. Across dietary treatments, activity of carnitine palmitoyltransferase (CPT) in hepatic mitochondria was lowest at - 21 d, highest at 1 d, and decreased at 21 and 65 d relative to parturition. The activity of CPT at d 1 tended to be higher for previously feed-restricted cows; thereafter, CPT activity declined more rapidly than in cows fed ad libitum. Nutrient intake during the dry period had more pronounced effects on peripartal lipid metabolism and DMI than did composition of the prepartum diet.

3-Hydroxybutyric Acid↗
PubMed2006

Diets during far-off and close-up dry periods affect periparturient metabolism and lactation in multiparous cows.

The objectives of this study were to determine the effects of far-off and close-up diets on prepartum metabolism, postpartum metabolism, and postpartum performance of multiparous Holstein cows. From dry-off to -25 d relative to expected parturition (far-off dry period), cows were fed a control diet to meet National Research Council (NRC) recommendations for net energy for lactation (NE(L)) at ad libitum intake (100NRC; n = 25) or a higher nutrient density diet, which was fed for either ad libitum intake to provide at least 150% of calculated NE(L) requirement (150NRC; n = 25) or at restricted intake to provide 80% of calculated NE(L) requirements (80NRC; n = 24). From -24 d relative to expected parturition until parturition (close-up period), cows were fed a diet that met or exceeded NRC nutrient recommendations at either ad libitum intake (n = 38) or restricted intake (n = 36) to provide 80% of the calculated NE(L) requirement. After parturition, all cows were fed a lactation diet and measurements were made through 56 d in milk (DIM). Prepartum metabolism was consistent with the plane of nutrition. During the first 10 DIM, far-off treatments had significant carryover effects on dry matter intake, energy balance, serum nonesterified fatty acid (NEFA) concentration, and serum beta-hydroxybutyrate concentration. Cows with the lower energy balance during the far-off period (100NRC and 80NRC) had higher dry matter intake and energy balance and lower serum NEFA and beta-hydroxybutyrate during the first 10 DIM. There were no effects of close-up diet and no interactions of far-off and close-up treatments. During the first 56 DIM, there were no residual effects of far-off or close-up diets on dry matter intake, milk yield or composition, body weight, body condition score, serum glucose and insulin concentrations, or muscle lipid concentration. Serum NEFA was higher for 150NRC than 80NRC; 100NRC was intermediate. Thus, the effects of far-off and close-up treatments on postpartum variables diminished as lactation progressed. Overfeeding during the far-off period had a greater negative impact on peripartum metabolism than did differences in close-up period nutrition.

3-Hydroxybutyric Acid↗
PubMed2006

Metabolic effects of abomasal L-carnitine infusion and feed restriction in lactating Holstein cows.

L-Carnitine is required for mitochondrial fatty acid oxidation, but the effects of carnitine supplementation on nutrient metabolism during dry matter intake depression have not been determined in dairy cows. Studies in other species have revealed responses to L-carnitine that may be of specific benefit to dairy cows during the periparturient period. Eight lactating Holstein cows (132 +/- 36 d in milk) were used in a replicated 4 x 4 Latin square experiment with 14-d periods. Treatments were factorial combinations of abomasal infusion of either water or L-carnitine (20 g/d; d 5 to 14) and either ad libitum or restricted intake (50% of previous 5-d dry matter intake; d 10 to 14) of a balanced lactation diet. Liver and muscle biopsies were obtained on d 14 of each period. Feed restriction induced negative balances of energy and metabolizable protein. In feed-restricted cows, carnitine infusion increased 3.5% fat-corrected milk yield compared with those infused with water. Total carnitine concentration in liver was increased in feed-restricted cows infused with carnitine but not in feed-restricted cows infused with water. Carnitine infusion stimulated in vitro oxidation of [1-(14)C] palmitate to acid-soluble products and decreased the proportion of [1-(14)C] palmitate that was converted to esterified products by liver slices. Feed-restricted cows infused with carnitine had lower liver total lipid concentration and tended to have decreased triglyceride accumulation compared with feed-restricted cows infused with water. Plasma nonesterified fatty acid concentration was not altered by carnitine infusion but was increased by feed restriction; serum beta-hydroxybutyric acid was increased by carnitine infusion in feed-restricted cows. In cows fed for ad libitum intake, carnitine infusion affected beta-hydroxybutyric acid, insulin, and urea N in serum, liver glycogen concentration, and in vitro alanine oxidation by liver slices, suggesting that hepatic and peripheral nutrient metabolism was influenced. L-Carnitine infusion effectively decreased liver lipid accumulation during feed restriction as a result of greater capacity for hepatic fatty acid oxidation. Further research examining dietary supplementation of L-carnitine during the periparturient period is warranted.

Abomasum↗
PubMed2005

Performance of dairy cows as affected by prepartum dietary carbohydrate source and supplementation with chromium throughout the transition period.

Holstein cows (n = 72) entering second or later lactation were used to determine whether productive performance and dry matter intake (DMI) are affected by carbohydrate source in the prepartum diet and chromium-L-methionine (Cr-Met) supplementation throughout the periparturient period. Cows were fed either a TMR with the concentrate portion based on starch-based cereals [high nonfiber carbohydrate (NFC); 1.59 Mcal/kg of net energy for lactation (NEL), 14.4% crude protein (CP), 40.3% NFC] or a TMR with the concentrate portion based on nonforage fiber sources (low NFC; 1.54 Mcal/kg NEL, 14.5% CP, 33.6% NFC) from 21 d before expected parturition until parturition. After parturition all cows were fed a lactation TMR (1.74 Mcal/kg NEL, 16.5% CP, 40.0% NFC). The Cr-Met was supplemented once daily via gelatin capsule at dosages of 0, 0.03, or 0.06 mg of Cr/kg of metabolic body weight. Thus, treatments were in a 2 (carbohydrate source) x 3 (Cr-Met) factorial arrangement. Neither prepartum nor postpartum DMI was affected by prepartum dietary carbohydrate source. Administering increasing amounts of Cr-Met linearly increased milk yield and, subsequently, postpartum DMI. Prepartum carbohydrate source did not affect postpartum milk yield; however, cows fed the low NFC diet tended to yield milk with a lower content of total solids. These data indicate that prepartum carbohydrate source has little influence on performance during the immediate peripartal period, and that increases in milk yield for cows supplemented with Cr-Met are independent of prepartum dietary carbohydrate source.

Animals↗
PubMed2005

Dry matter intake is decreased more by abomasal infusion of unsaturated free fatty acids than by unsaturated triglycerides.

Previous experiments from our group have demonstrated that abomasal infusion of unsaturated free fatty acids (FFA) markedly decreases dry matter intake (DMI) in dairy cows. In contrast, experiments from other groups have noted smaller decreases in DMI when unsaturated triglycerides (TG) were infused postruminally. Our hypothesis was that unsaturated FFA would be more potent inhibitors of DMI than an equivalent amount of unsaturated TG. Four Holstein cows in late lactation were used in a single reversal design. Cows were fed a total mixed ration containing (DM basis) 23% alfalfa silage, 23% corn silage, 40.3% ground shelled corn, and 10.5% soybean meal. Two cows received soy FFA (UFA; 0, 200, 400, 600 g/d) and 2 received soy oil (TG) in the same amounts; cows then were switched to the other lipid source. Cows were abomasally infused with each amount for 5-d periods. The daily amount of lipid was pulse-dosed in 4 equal portions at 0600, 1000, 1700, and 2200 h; no emulsifiers were used and there was no sign of digestive disturbance. Both lipid sources linearly decreased DMI, with a significant interaction between lipid source and amount. Slope-ratio analysis indicated that UFA were about 2 times more potent in decreasing DMI than were TG. Decreased DMI led to decreased milk production. Milk fat content was increased linearly by lipid infusion. Milk fat yield decreased markedly for UFA infusion but was relatively unaffected by infusion of TG. Contents of short- and medium-chain fatty acids in milk fat decreased as the amount of either infusate increased. Contents of C(18:2) and C(18:3) in milk fat were increased linearly by abomasal infusion of either fat source; cis-9 C(18:1) was unaffected. Transfer of infused C(18:2) to milk fat was 35.6, 42.5, and 27.8% for 200, 400, and 600 g/d of UFA, and 34.3, 39.6, and 34.0% for respective amounts of TG. Glucagon-like peptide-1 (7-36) amide (GLP-1) concentration in plasma significantly increased as DMI decreased with increasing infusion amount of UFA or TG. Plasma concentration of cholecystokinin-octapeptide (CCK-8) was unaffected by lipid infusion. These results indicate that unsaturated FFA reaching the duodenum are more potent inhibitors of DMI than are unsaturated TG; the effect may be at least partially mediated by GLP-1.

Abomasum↗
PubMed2005

Prepartum intake, postpartum induction of ketosis, and periparturient disorders affect the metabolic status of dairy cows.

Nutritional management during the dry period may affect susceptibility of cows to metabolic and infectious diseases during the periparturient period. Thirty-five multiparous Holstein cows were used to determine the effect of prepartum intake, postpartum induction of ketosis, and periparturient disorders on metabolic status. Cows were fed a diet from dry-off to parturition at either ad libitum intake or restricted intake [RI; 80% of calculated net energy for lactation (NEL) requirement]. After parturition, all cows were fed a lactation diet. At 4 d in milk (DIM), cows underwent a physical examination and were classified as healthy or having at least one periparturient disorder (PD). Healthy cows were assigned to the control (n = 6) group or the ketosis induction (KI; n = 9) group. Cows with PD were assigned to the PD control (PDC; n = 17) group. Cows in the control and PDC groups were fed for ad libitum intake. Cows in the KI group were fed at 50% of their intake on 4 DIM from 5 to 14 DIM or until signs of clinical ketosis were observed; then, cows were returned to ad libitum intake. During the dry period, ad libitum cows ate more than RI cows; the difference in intake resulted in ad libitum cows that were in positive energy balance (142% of NEL requirement) and RI cows that were in negative energy balance (85% of NEL requirement). Prepartum intake resulted in changes in serum metabolites consistent with plane of nutrition and energy balance. Prepartum intake had no effect on postpartum intake, serum metabolites, or milk yield, but total lipid content of liver at 1 d postpartum was greater for ad libitum cows than for RI cows. The PD cows had lower intake and milk yield during the first 4 DIM than did healthy cows. During the ketosis induction period, KI cows had lower intake, milk yield, and serum glucose concentration but higher concentrations of nonesterified fatty acids and beta-hydroxybutyrate in serum as well as total lipid and triacylglycerol in liver than did control cows. Cows with PD had only modest alterations in metabolic variables in blood and liver compared with healthy cows. The negative effects of PD and KI on metabolic status and milk yield were negligible by 42 DIM, although cows with PD had lower body condition score and BW. Prepartum intake did not affect postpartum metabolic status or milk yield. Periparturient disorders and induction of ketosis negatively affected metabolic status and milk yield during the first 14 DIM.

3-Hydroxybutyric Acid↗
PubMed2005

Carnitine palmitoyltransferase I in liver of periparturient dairy cows: effects of prepartum intake, postpartum induction of ketosis, and periparturient disorders.

Thirty-five multiparous Holstein cows were used to determine the role of mitochondrial carnitine palmitoyltransferase I (CPT I) in liver on peripartal adaptations of fatty acid metabolism. From dry-off to parturition, cows were fed a diet at either ad libitum (n = 17) or restricted intake (RI, 80% of calculated requirements for net energy; n = 18). After parturition, all cows were fed a lactation diet. At 4 d in milk (DIM), cows underwent a physical examination and were classified as healthy (n = 15) or having at least one periparturient disorder (PD; n = 17). Cows in the healthy group were assigned to either a control (n = 6) group or a ketosis induction (KI; n = 9) group. Cows with periparturient disorders were assigned to a third (PDC; n = 17) group. Cows in control and PDC groups were fed for ad libitum intake. Cows in KI were fed at 50% of their respective intake at d 4 postpartum starting from 5 DIM and continuing to signs of clinical ketosis or until 14 DIM; cows then were returned to ad libitum intake. Liver was biopsied at -30 d, 1 d, at signs of clinical ketosis or 14 d, and 28 d relative to parturition. Mitochondria were isolated by differential centrifugation. Activity of CPT I was 5.4 and 7.6 nmol of palmitoylcarnitine formed per min/mg of protein for ad libitum and RI, respectively, at -30 DIM. Sensitivity of CPT I to its inhibitor, malonyl CoA, did not differ between ad libitum and RI cows. Differences in CPT I activity between ad libitum and RI were no longer significant at 1 DIM. Postpartum CPT I activity and malonyl CoA sensitivity at 1 DIM, onset of clinical ketosis or 14 DIM, and 28 DIM were not affected by prepartum intake (ad libitum vs. RI), postpartum health status (healthy vs. PD), or ketosis induction status (control vs. KI vs. PDC). Activity of CPT I was positively correlated with liver total lipid, liver triglyceride, liver triglyceride to glycogen ratio, and serum nonesterified fatty acids. Activity of CPT I and dry matter intake were not correlated. Prepartum intake affected prepartum CPT I activity but not malonyl CoA sensitivity. Neither induction of primary ketosis nor periparturient disorders greatly affected CPT I activity or sensitivity, which indicates that alterations of CPT I may not be a major factor in the etiology of primary ketosis or other periparturient disorders.

3-Hydroxybutyric Acid↗
PubMed2004

Peripartal metabolism and production of holstein cows fed diets supplemented with fat during the dry period.

Previous research from our laboratory demonstrated that cows fed supplemental fat throughout the dry period in an attempt to increase body condition score (BCS) had little hepatic lipid accumulation at d 1 postpartum compared with cows fed an isocaloric high-grain diet or a lower energy control diet. However, results were confounded by lower dry matter intake and loss of BCS by cows fed the fat-supplemented diet. Here, cows were fed a control diet (C) moderately high in nonfiber carbohydrates (NFC) or an isocaloric fat-supplemented, low NFC (F) diet to reassess the effects of supplemental fat throughout the dry period on peripartal lipid accumulation in liver. A more energy-dense, high-NFC diet supplemented with fat (CF) was also fed to test the efficacy of supplemental fat in a diet with similar carbohydrate composition but higher energy density. Intakes of dry matter and net energy for lactation were similar among treatments throughout the experiment, although diet x day interactions during the last 21 d before parturition indicated that cows fed CF decreased intakes more slowly. Cows gained similar amounts of BCS and body weight among diets prepartum, but cows fed C tended to lose more BCS and body weight around parturition. Milk production and milk components did not differ among treatments. Prepartum concentrations of glucose, insulin, total protein, nonesterified fatty acids, and mu-hydroxybutyrate in plasma were similar among treatments. Supplemental fat increased prepartum concentrations of urea and cholesterol in plasma. Postpartum concentrations of metabolites and insulin in plasma were similar among treatments. Concentrations of total lipid and triglyceride in liver increased at parturition, whereas hepatic glycogen concentration decreased, but concentrations were not different among treatments. Supplemental fat fed prepartum did not affect peripartal lipid accumulation in liver tissue and did not benefit postpartum milk production.

Analysis of Variance↗
PubMed2003

Effect of photoperiod on hepatic growth hormone receptor 1A expression in steer calves.

Photoperiod manipulation, specifically a long-day photoperiod (LDPP), increases milk production in lactating cattle. We have previously reported that the galactopoietic effect of LDPP is associated with an increase in circulating IGF-I, which seems to occur independently of changes in concentrations of GH, IGFBP-2, and IGFBP-3. This study tested the hypothesis that LDPP increases the expression of GH receptor (GHR) 1A messenger RNA (mRNA) in the liver. Two groups of Holstein steer calves (98 +/- 4 d old) were maintained indoors and exposed to LDPP (16-h light: 8-h dark; n = 6) or short-day photoperiod (SDPP; 8-h light: 16-h dark; n = 6) for 60 d. Calves were individually fed a grain- and alfalfa-based diet. Jugular blood samples were collected weekly and via cannula at 15-min intervals for a 4-h period on d 1, 26, and 55 of the study to monitor pulsatile hormone secretion. Serum was harvested and assayed for IGF-I, prolactin (PRL), and GH using RIA. Liver biopsies were obtained at 3-wk intervals to quantify changes in hepatic IGF-I and GHR 1A mRNA using real-time PCR. Steer BW increased during the study but did not differ between treatments. No differences in ADG or total DMI were observed. Relative to SDPP, calves on LDPP had higher (P < 0.05) serum IGF-I concentrations. Concentrations of PRL increased (P < 0.01) in calves exposed to LDPP compared with calves exposed to SDPP. Differences (P < 0.05) in pulsatile GH secretion were also detected. Hepatic IGF-I and GHR 1A mRNA were positively correlated with circulating IGF-I concentrations, and although both increased with time, they were not affected by photoperiod treatment. These results confirm that LDPP increases circulating concentrations of IGF-I, but this occurs independently of changes in IGF-I synthesis and GHR 1A mRNA expression in the liver. Therefore, our hypothesis that LDPP increases the expression of GHR 1A mRNA in the bovine liver is rejected.

Animal Feed↗
PubMed2003

Growth, nutrient utilization, and body composition of dairy calves fed milk replacers containing different amounts of protein.

Male Holstein calves < 1 wk of age were allowed a 2-wk adaptation period after purchase, and then were blocked by BW and assigned randomly within block to either a baseline slaughter group or one of four experimental groups (n = 8 to 9 per group). Treatments were isocaloric milk replacers (12.5% solids) fed at 12% of BW that contained 16.1, 18.5, 22.9, or 25.8% CP (DM basis) from whey protein sources. After a 6-wk feeding period, all calves were slaughtered and the weights and chemical composition of the viscera-free carcasses (VFC; including head, hide, feet, and tail) were determined. Gain of BW (0.38, 0.45, 0.56, and 0.62 kg/d) and gain:feed ratio (0.51, 0.59, 0.71, and 0.78) increased linearly (P < 0.001) as dietary CP increased; rate of change in body length, wither height, and heart girth also increased linearly (P < or = 0.05). Balance measurements conducted during wk 3 and 4 of the experimental period showed that both absorbed N (16.9, 20.0, 25.8, and 30.6 g/d) and retained N (7.6, 9.0, 13.2, and 15.6 g/d) increased linearly (P < 0.001) as dietary CP increased. Retained N as a percentage of absorbed N increased linearly (P < 0.01) as dietary CP increased (44.3, 44.7, 50.7, and 50.9%), whereas biological value was unaffected (71.1, 68.7, 69.5, and 67.3%; P = 0.26). Digestible energy and ME represented 94.5 and 89.7% of intake energy, respectively, and were not affected by dietary CP content. Plasma urea N concentration increased linearly (2.9, 3.3, 4.6, and 6.0 mg/dL) as dietary CP increased. Contents of water (68.2, 69.1, 70.2, and 70.5%; P < 0.001) and protein (19.6, 20.0, 20.0, and 20.2%; P < 0.10) in VFC increased linearly, whereas contents of fat (7.2, 6.2, 5.5, and 5.2%; P < 0.001) and ash (5.1, 5.2, 4.8, and 4.7%; P < 0.02) decreased linearly as dietary CP increased. Trends in visceral tissue composition were similar to those for VFC. The content of water in VFC tissue gain increased, whereas contents of fat and energy decreased, as dietary CP increased. Final VFC energy and gain of energy in VFC were not affected by dietary CP. At similar initial ME intakes, increasing dietary CP (i.e., increasing protein: energy) linearly increased ADG, gain:feed, N retention, and deposition of lean tissue in VFC, demonstrating that diet composition can markedly affect components of body growth in preruminant dairy calves.

Animal Feed↗
PubMed2003

Effects of tallow in diets based on corn silage or alfalfa silage on digestion and nutrient use by lactating dairy cows.

Six multiparous Holstein cows (average 31 days in milk; 36.3 kg/d of milk) fitted with ruminal cannulas were used in a 6 x 6 Latin square with 21-d periods to investigate the effects of diets that varied in forage source and amount of supplemental tallow. Isonitrogenous diets in a 2 x 3 factorial arrangement were based on either high corn silage (40:10 corn silage to alfalfa silage, % of dry matter) or high alfalfa silage (10:40 corn silage to alfalfa silage, % of dry matter) and contained 0, 2, or 4% tallow. Intakes of dry matter and total fatty acids were lower when cows were fed the high corn silage diet. Tallow supplementation linearly decreased dry matter intake. Milk yield was unaffected by diet; yields of milk fat and 3.5% fat-corrected milk were higher for the high alfalfa silage diet but were unaffected by tallow. Milk fat percentage was higher for the high alfalfa silage and tended to decrease when tallow was added to the high corn silage diet. Contents of trans-C18:1 isomers in milk fat were increased by high corn silage and tallow, and tended to be increased more when tallow was fed in the high corn silage diet. Ruminal pH and acetate:propionate were lower when high corn silage was fed. Ruminal acetate:propionate decreased linearly as tallow increased; the molar proportion of acetate was decreased more when tallow was added to the high corn silage diet. Ruminal liquid dilution rates were higher for the alfalfa silage diet; ruminal volume and solid passage rates were similar among diets. Total tract apparent digestibilities of dry matter, organic matter, crude protein, starch, energy, and total fatty acids were unaffected by diet. Digestibilities of neutral detergent fiber, acid detergent fiber, hemicellulose, and cellulose were lower when high corn silage was fed. The high alfalfa silage diet increased intakes of metabolizable energy and N, and increased milk energy and productive N. Tallow decreased the amount of N absorbed but had few other effects on utilization of energy or N. Tallow linearly increased concentrations of nonesterified fatty acids and cholesterol in plasma; cholesterol was increased by high alfalfa silage. Overall, forage source had more pronounced effects on production and metabolism than did tallow supplementation. Few interactions between forage source and tallow supplementation were detected except that ruminal fermentation and milk fat content were affected more negatively when tallow was fed in the high corn silage diet.

Animal Nutritional Physiological Phenomena↗
PubMed2003

Responses of primiparous and multiparous Holstein cows to additional energy from fat or concentrate during summer.

Supplemental fat has been advocated for use during hot weather and often increases milk yield of cows past peak production when energy intake should not be limiting. Relative responses of primiparous and multiparous cows to supplemental fat or isocaloric addition of concentrates under hot weather conditions have not been determined. Nine multiparous and nine primiparous Holstein cows (154 and 167 d in milk, respectively) were used in a replicated 3 x 3 Latin square design with 28-d periods. Diets were 1) control (35% alfalfa silage, 25% corn silage, and 40% concentrate, dry matter [DM] basis); 2) control plus 3% fat (HF); and 3) high concentrate ([HC] 15% alfalfa silage, 25% corn silage, and 60% concentrate). Diets were isonitrogenous; diets HF and HC were isocaloric (1.60 Mcal of net energy for lactation [NE(L)] per kilogram DM) and higher energy than the control (1.52 Mcal/kg). No parity x diet interactions approached significance. DM intake (DMI) was greater when cows were fed HC than when they were fed HF (21.0, 20.1, and 21.3 kg/d for control, HF, and HC, respectively); intake of NE(L) tended to be increased only for HC. Milk yield was increased by higher-energy diets, but milk fat content was decreased. Milk total protein content was decreased by HF and increased by HC. Yield of solids-corrected milk (SCM) was not different among diets. Efficiency of milk production, expressed either as total milk solids yield per kilogram of DMI or as kilograms of SCM per megacalorie of NE(L) intake, was greater for HF than for HC. Plasma glucose was higher after feeding for cows fed HC; plasma nonesterified fatty acids were greater for HF. Respiration rate and rectal temperature were greater for HC than for HF. Regardless of parity, increased energy density from either fat or concentrate increased milk yield in midlactation cows, but diets caused energy to be partitioned differently among milk components and body storage. Supplemental rumen-active fat had modest advantages over additional starch-based concentrate during summer heat conditions.

Animals↗
PubMed2002

Concentrations of conjugated linoleic acid (cis-9, trans-11-octadecadienoic acid) are not increased in tissue lipids of cattle fed a high-concentrate diet supplemented with soybean oil.

Conjugated linoleic acid (CLA), a mixture of isomers of linoleic acid, has many beneficial effects, including decreased tumor growth in animal cancer models. The cis-9, trans-11 isomer of CLA (CLA9,11) can be formed in the rumen as an intermediate in biohydrogenation of linoleic acid. Recent data, however, indicate that tissue desaturation of trans-fatty acids is an important source of CLA9,11 in milk. Our objective was to determine whether supplementing a high-corn diet with soybean oil (SBO; a source of linoleic acid) would increase concentrations of CLA in ruminal contents and tissue lipids. Four ruminally cannulated steers were utilized in a Latin square design with 28-d periods. A control diet (80% cracked corn, 2.0% corn steep liquor, 8.0% ground corn cobs, and 10% supplement [soybean meal, ground shelled corn, minerals, and vitamins]) was supplemented with 2.5, 5.0, or 7.5% (DM basis) SBO. Supplemental SBO did not affect ruminal pH or concentrations of the major VFA. The proportion and amount (mg FA/g DM ruminal contents) of CLA9,11 were not increased by increasing dietary SBO. However, the proportion and amount of the trans-10, cis-12 CLA isomer (CLA10,12) in ruminal contents increased linearly (P < 0.006) as dietary SBO increased. Trans-18:1 isomers in ruminal contents increased linearly (P < 0.02) as dietary SBO increased. The proportion of CLA10,12 was correlated positively (P < 0.001) with proportions of trans-C 18:1 isomers in ruminal contents. Conversely, CLA9,11 was correlated negatively (P < 0.05) with the proportions of trans-18:1 in ruminal contents. The same high-corn diet, supplemented with 0 or 5% SBO, was fed to 20 Angus-Wagyu heifers for 102 d in a randomized complete block design to determine the effect of added SBO on tissue deposition of CLA. Supplemental SBO did not affect feed intake, gain:feed, or carcass quality. Tissue samples were obtained from the hindquarter, loin, forequarter, liver, large and small intestine, and subcutaneous, mesenteric, and perirenal adipose depots. The concentration of CLA9,11 was greatest in subcutaneous adipose tissue but was not affected in any tissue by SBO. Supplementing high-corn diets with SBO does not increase CLA9,11 concentrations in tissues of fattening heifers. Research is needed to identify regulatory factors for pathways of biohydrogenation that lead to increased concentrations of CLA10,12 in ruminal contents when high-oil, high-concentrate diets are fed.

Adipose Tissue↗
PubMed2002

Isolated canine and murine intestinal cells exhibit a different pattern of fuel utilization for oxidative metabolism.

The amount and type of dietary fiber influences the end-products of fermentation and thus fuel availability to intestinal tissue. Metabolic fuel usage was studied in intestinal cells isolated from dogs consuming a commercial diet or from rats consuming either a commercial rat diet or dog diet to examine preferential fuel usage, the effect of diet, and species differences. Production of 14CO2 was measured by incubating cells in media containing either D-[U-14C]glucose, [1-14C]n-butyrate, L-[U-14C]glutamine, or [1-14C]propionate with or without competing substrates. The presence of a mixture of 5 mM each of glucose, butyrate, propionate, and acetate and 1 mM glutamine in the media decreased CO2 production from glucose, glutamine, and propionate by canine enterocytes (P < 0.05) and from glutamine and propionate by canine colonocytes (P < 0.05). The presence of glutamine in the media decreased glucose oxidation by murine enterocytes, regardless of the diet. Similarly, glutamine decreased glucose oxidation by murine colonocytes (P < 0.05), but only when the rats had consumed the rat diet. Regardless of diet, murine colonocytes oxidized more butyrate (P < 0.01) than did enterocytes, and murine enterocytes tended (P < 0.07) to oxidize more glucose than did colonocytes. The proportion of propionate in colonic contents was higher in dogs than in rats (P < 0.02), and the proportion of butyrate tended to be higher in contents from rats than in those from dogs (P < 0.08). Colonic and cecal wet weights were decreased (P < 0.05) when rats were fed the commercial dog diet. Preferred utilization of substrates by isolated canine enterocytes and colonocytes differed from that of murine intestinal cells. These differences were only partially overcome by feeding the same diet to each species.

Acetates↗