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1.
Methionine as a methyl group donor in growing cattle   总被引：2，自引：0，他引：2  
Holstein steers were used in two 5 x 5 Latin square experiments to evaluate the sparing of methionine by alternative sources of methyl groups (betaine and choline). Steers were housed in metabolism crates and limit-fed a soybean hull-based diet high in rumen degradable protein. To increase energy supply, ruminal infusions of volatile fatty acids and abomasal infusions of glucose were provided. An amino acid mixture, limiting in methionine, was infused abomasally to ensure that nonsulfur amino acids did not limit protein synthesis. Treatments for Exp. 1 were abomasal infusion of 1) water, 2) 2 g/d L-methionine, 3) 1.7 g/d L-cysteine, 4) 1.6 g/d betaine, and 5) 1.7 g/d L-cysteine + 1.6 g/d betaine. Treatments for Exp. 2 were abomasal infusion of 1) water, 2) 2 g/d L-methionine, 3) 8 g/d betaine, 4) 16 g/d betaine, and 5) 8 g/d choline. In both experiments, nitrogen retention increased in response to methionine (P < 0.05), demonstrating a deficiency of sulfur amino acids. Responses to cysteine, betaine, and choline were all small and not significant. The lack of response to cysteine indicates that the response to methionine was not due to transsulfuration to cysteine or that cysteine supply did not alter the flux of methionine through transsulfuration. The lack of response to betaine suggests that the steers' needs for methyl groups were met by the dietary conditions or that betaine was relatively inefficient in increasing the remethylation of homocysteine to methionine and, thereby, reducing the synthesis of cysteine from homocysteine. Under our experimental conditions, responses to methionine were likely due to a correction of a deficiency of methionine per se rather than of methyl group donors.  相似文献   

2.
Two experiments were conducted with ruminally cannulated Holstein steers to determine effects of N supply on histidine (His) utilization. All steers received 2.5 kg DM/d of a diet based on soybean hulls; abomasal infusion of 250 g/d amino acids, which supplied adequate amounts of all essential amino acids except His; abomasal infusion of 300 g/d glucose; and ruminal infusion of 180 g/d acetate, 180 g/d propionate, and 45 g/d butyrate. Both experiments were 6 x 6 Latin squares with treatments arranged as 3 x 2 factorials. No significant (P < 0.05) interactions between main effects were noted for N balance criteria in either Exp. 1 or 2. For Exp. 1, steers (146 +/- 7 kg) received 0, 1.5, or 3 g/d of L-His infused abomasally in combination with 0 or 80 g/d urea infused ruminally to supply a metabolic ammonia load. Urea infusions increased (P < 0.05) ruminal ammonia concentration from 8.6 to 19.7 mM and plasma urea from 2.7 to 5.1 mM. No change in N retention occurred in response to urea (35.1 and 37.1 g/d for 0 and 80 g/d urea, respectively, P = 0.16). Retained N increased linearly (P < 0.01) with His (31.5, 37.8, and 39.0 g/d for 0, 1.5, and 3 g/d L-His, respectively). Efficiency of deposition of supplemental His between 0 and 1.5 g/d averaged 65%. In Exp. 2, steers (150 +/- 6 kg) were infused abomasally with 0 or 1 g/d of L-His in combination with no additional amino acids (Control), 100 g/d of essential + 100 g/d of nonessential amino acids (NEAA+EAA), or 200 g/d of essential amino acids (EAA). Retained N increased (P = 0.02) from 34.2 to 38.3 g/d in response to His supplementation. Supplementation with NEAA+EAA increased (P < 0.05) N retention (33.9, 39.3, and 35.6 g/d for Control, NEAA+EAA, and EAA, respectively), likely in response to increased energy supply. Plasma urea concentrations of steers receiving NEAA+EAA (3.8 mM) and EAA (3.8 mM) were greater (P < 0.05) than those of Control steers (2.7 mM). The average efficiency of His utilization was 63%, a value similar to the value of 65% observed in Exp. 1, as well as the 71% value predicted by the Cornell net carbohydrate and protein system model. Under our experimental conditions, increases in N supply above requirements, as either ammonia or amino acids, did not demonstrate a metabolic cost in terms of His utilization for whole-body protein deposition by growing steers.  相似文献   

3.
Five studies were conducted to evaluate the effects of lipid source on performance and health of stressed feeder cattle. A total of 332 heifers (195 +/- 2.37 kg initial BW) in trial 1 and 336 heifers (206 +/- 1.70 kg initial BW) in trial 2 were fed diets containing ground flaxseed (FLAX), rolled full-fat soybeans (SOY), or tallow (TAL) at 13, 20, or 4%, respectively (DM basis). All diets were formulated to be isonitrogenous and isocaloric. The ADG and G:F for the first 7 d and for the entire feeding period were greater (P < 0.05) for TAL and FLAX than for SOY. Percentage of animals treated and retreated for bovine respiratory disease did not differ among dietary treatments. The FLAX treatment increased (P < 0.05) total n-3 PUFA concentrations in the plasma, whereas SOY increased (P < 0.05) plasma concentrations of total n-6 PUFA. In trial 3, 18 steers were individually fed diets containing TAL and 18 steers were fed a diet containing SOY (20% of DM). In trials 4 and 5, 18 steers were individually fed diets containing TAL and 18 steers were fed diets containing FLAX (12.9% of DM). On d 14 and 17 of study 3, 4, and 5, 16 steers from each dietary treatment were injected i.v. with Escherichia coli O55:B5 lipopolysaccharide (LPS), and 2 steers from each diet were injected with saline. Rectal temperatures after LPS challenge were lower (P < 0.05) for SOY and FLAX than for TAL, and plasma TNF was greater (P < 0.05) for SOY than for TAL. Serum haptoglobin and blood fibrinogen increased and white blood cell count decreased in response to LPS, but none of these variables was affected by treatment. Although this research failed to measure an effect of lipid source on feedlot morbidity or mortality, these studies indicate that altering the source and type of dietary fatty acids may modify the immune response in stressed feeder cattle and that performance may be hindered by feeding full-fat soybeans to receiving cattle.  相似文献   

4.
Six ruminally cannulated Holstein steers (initial BW = 189 +/- 11 kg) housed in metabolism crates were used in a 6 x 6 Latin square to study effects of ruminal ammonia load on Leu utilization. All steers received a diet based on soybean hulls (2.7 kg of DM/d), ruminal infusions of 200 g of acetate/d, 200 g of propionate/d, and 50 g of butyrate/d, as well as an abomasal infusion of 300 g of glucose/d to provide energy without increasing microbial protein supply and an abomasal infusion of a mixture (238 g/d) of all essential AA except Leu. Treatments were arranged as a 3 x 2 factorial and included Leu (0, 4, or 8 g/d) infused abomasally and urea (0 or 80 g/d) infused ruminally. Abomasal Leu infusion linearly decreased (P < 0.05) both urinary and fecal N excretions and linearly increased (P < 0.05) retained N, but the decreases in urinary N excretion in response to Leu tended (P = 0.07) to be greater, and the increases in retained N in response to Leu were numerically greater in the presence of the urea infusion. Although urea infusions increased (P < 0.05) plasma urea concentrations, urinary N excretions, and urinary urea excretions, retained N also was increased (P < 0.05). The efficiency of deposition of supplemental Leu ranged from 24 to 43% when steers received 0 or 80 g of urea/d, respectively. Under our experimental conditions, increasing ammonia load improved whole-body protein deposition in growing steers when Leu supply was limiting.  相似文献   

5.
Seven ruminally cannulated Holstein steers (194 +/- 16 kg) housed in metabolism crates were used in a 6 x 6 Latin square, with one additional steer, to study effects of ruminal ammonia load on methionine (Met) use. All steers received a diet based on soybean hulls (2.6 kg DM/d), ruminal infusions of 200 g/d of acetate, 200 g/d of propionate, and 50 g/d of butyrate, as well as abomasal infusion of 300 g/d of glucose to provide energy without increasing microbial protein supply, and abomasal infusions of a mixture (248 g/d) of all essential AA except Met. Treatments were arranged as a 3 x 2 factorial and included urea (0, 40, or 80 g/d) infused ruminally to supply metabolic ammonia loads and Met (2 or 5 g/d) infused abomasally. Supplementation with the greater amount of Met decreased (P < 0.05) urinary N excretion from 68.8 to 64.8 g/d and increased (P < 0.05) retained N from 22.0 to 27.5 g/d. Urea infusions linearly increased (P < 0.05) urinary N excretions, plasma urea concentrations, and urinary urea excretions, but retained N was not affected. The efficiency of deposition of supplemental Met, calculated by assuming that Met deposition is 2.0% of protein deposition (6.25 x retained N), ranged between 18 and 27% when steers received 0 or 80 g/d of urea, respectively. There were no (P > or = 0.40) effects of treatments on serum insulin or IGF-I concentrations. In our model, increasing ammonia load did not affect whole-body protein deposition in growing steers when Met was limiting.  相似文献   

6.
An experiment was conducted to evaluate the effects of grain processing and lipid addition to finishing diets on cattle performance, carcass characteristics, and meat quality. Eighty Hereford x Angus steers (384 kg +/- 17 kg of BW) were fed diets containing steam-flaked corn (SFC) or dry-rolled corn (DRC) with and without the addition of tallow (SFC/Fat and DRC/Fat) or steam-flaked corn with ground flaxseed (SFC/Flax). Ribeye steaks from steers fed SFC, SFC/Fat, or SFC/ Flax were used to evaluate the effects of fat source on meat quality. Cattle fed SFC and SFC/Fat tended to have greater ADG, G:F, HCW, and USDA yield grade, compared with those fed DRC and DRC/Fat (P < 0.10). Steaks from steers fed SFC/Flax developed a detectable off-flavor (P < 0.05) compared with steaks from steers fed SFC and SFC/Fat, and steaks from steers fed SFC retained desirable color longer than those from steers fed SFC/Flax (P < 0.05). Feeding SFC/Flax increased deposition of alpha-linolenic acid in muscle tissue compared with feeding SFC or SFC/Fat (P < 0.01). Dietary treatment did not cause differences in tenderness, juiciness, or flavor intensity. Ground flaxseed can replace tallow in finishing diets without loss in performance, but flax may affect flavor and color stability of beef. Feeding flaxseed can effectively alter composition of carcass tissues to yield beef that is high in n-3 fatty acids.  相似文献   

7.
Effects of zinc sulfate (0 vs 1,142 ppm supplemental zinc from zinc sulfate) and feeding frequency (1 x vs 12x daily) on ruminal protozoa numbers, fermentation patterns and amino acid passage were investigated using four ruminally and abomasally cannulated mature Jersey steers in a 4 x 4 Latin square experiment. Steers (530 kg) were fed a 50:50 roughage:concentrate diet at 1.5 times their NEm requirement. Experimental periods were 14 d in duration; ruminal, abomasal and fecal samples were collected at 6-h intervals during the last 3 d of each period. Protozoa numbers tended to be lowest (1.82 x 10(6)/ml) in steers fed zinc 1 x and tended to be highest (3.83 x 10(6)/ml) in steers fed zinc 12 x daily (P less than .10). Frequent feeding decreased ruminal pH .24 units and increased total VFA 20.7%, ammonia 22.7% and ruminal digestion of dietary amino acids (AA) 61.6% (P less than .05). Zinc supplementation decreased ruminal digestion of dietary AA 35.8% (P less than .05) and the abomasal passage of bacterial OM and AA 21.2% (P less than .05) and increased ruminal output of amino acids as a percentage of intake 15.1% (P less than .05). Although it increased escape of dietary AA, zinc sulfate decreased postruminal passage of bacterial AA and resulted in a net negative effect on total postruminal AA passage as a percentage of intake. The effects of zinc on ruminal AA digestion may be more closely related to an interaction of zinc with dietary CP rather than to an effect of Zn on ruminal microbial populations.  相似文献   

8.
To measure the effects of dietary fat on feedlot performance and carcass characteristics, and on beef appearance, moisture binding, shelf life, palatability, and fatty acid content, 126 crossbred beef steers (321.1 +/- 0.57 kg of BW) were allotted to a randomized complete block (3) design with a 3 x 2 + 1 factorial arrangement of dietary treatments. The main effects were level of yellow grease (0, 3, or 6%) and alfalfa hay (3.5 or 7%) in corn-based diets containing 15% potato by-product (PB). The added treatment was 6% tallow and 7% alfalfa in a barley-based diet containing 15% PB. Dry matter intake and ADG were not affected by diet; however, G:F and diet NE content increased linearly (P < 0.10) with yellow grease. Kidney, pelvic, and heart fat (2.0 to 2.3 +/- 0.07) and yield grade (2.8 to 3.1 +/- 0.09) increased linearly (P < or = 0.05) with yellow grease. Steers fed corn plus 6% yellow grease had lower (P < 0.05) beef firmness and beef texture scores but greater (P < 0.01) fat color score than those fed barley plus 6% tallow. Moisture retention of beef was not affected by dietary treatment, except purge score during retail storage, which was decreased linearly (P < 0.01) from 2.1 to 1.6 +/- 0.06 by level of yellow grease. Steaks from steers fed barley plus 6% tallow had greater (P < 0.05) shear force than those from steers fed corn plus 6% yellow grease, and beef flavor increased linearly (P < 0.05) from 6.2 to 6.7 +/- 0.11 as the level of yellow grease increased. Level of yellow grease linearly increased (P < 0.01) transvaccenic acid (TVA) by 61% and CLA content of beef by 48%. Beef from steers fed corn plus yellow grease had lower (P < 0.05) palmitoleic and oleic acids and greater (P < 0.05) linoleic, TVA, and CLA than beef from steers fed the barley-tallow diet. Feeding yellow grease increased diet energy content, which increased carcass fatness, and altered beef fatty acid content, which increased beef flavor without affecting moisture retention, shelf life, or cooking properties of the beef. Additionally, beef from steers fed corn plus 6% yellow grease was more tender and had more polyunsaturated fatty acid content and CLA than beef from steers fed barley plus 6% tallow.  相似文献   

9.
Use of poultry fat in the finishing diets of steers has not been studied as a potential source of added energy. Therefore, 60 Angus crossbred steers were fed 1 of 3 dietary treatments consisting of 1) a corn-soybean meal control diet devoid of added fat; 2) the control diet formulated with 4% tallow; or 3) the control diet formulated with 4% poultry fat. Addition of fat did not (P = 0.17) affect ADG for the 112-d study. The inclusion of tallow in the diet reduced (P < 0.05) ADFI of steers compared with those on the control diet; however, ADFI of steers fed poultry fat did not differ from those fed the control (P = 0.06) or the tallow (P = 0.36) diets. At d 55, steers consuming either fat source had improved (P < 0.05) G:F compared with steers fed the control diet. For the entire 112 d, steers consuming the poultry fat diet gained more efficiently (P < 0.05) than the control steers, and the tallow-fed steers were intermediate and not different from the other groups (P > or = 0.14). The inclusion of fat in the diet did not (P > or = 0.15) affect carcass characteristics. Steaks from the steers consuming diets with added fat were darker (lower L* value; P < 0.05) than the controls; however, dietary treatments did not (P > or = 0.10) affect any other objective color measurements or discoloration scores during retail display. Thiobarbituric acid reactive substances for LM steaks did not differ (P = 0.21) by dietary treatment. The cooked LM steaks from steers fed poultry fat did not (P > or = 0.80) differ in juiciness or flavor intensity from steaks of steers fed the control or tallow diets. There were also no differences (P = 0.18) in off flavors as a result of added dietary fat. In the LM and adipose tissue, percentages of total SFA were increased (P = 0.05) by adding supplemental fat to the diet, regardless of source. In the LM, total MUFA were decreased (P = 0.02) by adding supplemental fat. Conversely, diet did not (P > or = 0.14) affect the proportions of total PUFA in either tissue or total MUFA in the adipose tissue. Results indicated that replacing beef tallow in finishing diets with poultry fat, a more economical energy source, had no detrimental effects on growth performance, carcass characteristics, retail display life, fatty acid profiles, or palatability.  相似文献   

10.
Sixty ribeye steaks were used to determine the effects of anabolic implants on i.m. lipid composition of beef steers. Steaks were obtained from carcasses (346 kg) of steers assigned to four treatment groups (C = nonimplanted control; ET = 28 mg of estradiol benzoate plus 200 mg of trenbolone acetate on d 0; ET/ET = ET on d 0 and d 61; and S/ET = 20 mg of estradiol benzoate plus 200 mg of progesterone on d 0 and ET on d 61) and fed a high-concentrate diet for 127 d. Total fatty acid content of the longissimus was less (P < .05) for implanted steers. Implanting increased (P < .05) stearic and linolenic acid percentages and reduced (P < .05) oleic acid percentage but did not alter (P > .05) percentages of other fatty acids. These changes translated into increased (P < .05) percentages of saturated fatty acids and reduced (P < .05) monounsaturated fatty acids in the longissimus of implanted steers. However, on a per-steak weight basis, implanting did not alter (P > .05) the amounts of any of the individual fatty acids, but it increased (P < .05) the total cholesterol amount. Implanting with an estrogenic compound first reduced (P < .05) the percentage and total amounts of linoleic and polyunsaturated fatty acids. On a percentage basis, implanting alters fatty acid amounts; however, when the increase in ribeye size with implanting is accounted for and fatty acids are evaluated on a per-steak basis, these differences are not significant.  相似文献   

11.
Two trials that utilized 356 yearling steers were conducted to evaluate the effects of fat sources (3.5% of diet dry matter) in steam-flaked milo finishing diets. Fats differed in fatty acid composition and level of free fatty acids. In Trial 1, soybean oil, tallow and yellow grease were compared to a nonfat control. Feeding fat increased (P less than .05) daily gain, feed efficiency, estimated diet NE concentration, carcass weight and dressing percentage of steers. In Trial 2, fat treatments were control, acidulated soybean soapstock (SBSS), tallow, a blend of 70% SBSS:30% tallow, and yellow grease. Feeding tallow or the SBSS:tallow blend improved (P less than .05) feed efficiency and estimated dietary NE compared to control. Proportions of palmitic, stearic, oleic, linoleic and linolenic acid in longissimus muscle of steers were altered (P less than .05) by source of supplemental fat. Potential variability in animal response to fat blends was demonstrated by differences in animal response to yellow grease in the two trials. It was concluded that fats vary in feeding value and may alter carcass composition, contrary to putative thought. Further, potential associative effects of fat blends and interactions of fat with other dietary components in high-grain finishing diets require further investigation.  相似文献   

12.
Five steers (mean BW 526 kg) fitted with ruminal, duodenal, and ileal cannulas were used in a 5 x 6 Youden square design with 14-d periods. Diets contained chopped alfalfa hay, corn silage, and concentrate (25:35:40, DM basis). Treatments were 1) control (no added fat); 2) tallow (T), iodine value (IV) = 51.5; 3) partially hydrogenated tallow (PHT), IV = 30.7; 4) hydrogenated tallow (HT), IV = 6.9; 5) blend (1: 1) of HT and hydrogenated free fatty acids (HTHFA), IV = 9.0; and 6) hydrogenated free fatty acids (HFA), IV = 11.2. Fats replaced cornstarch in the control diet to supply 5% added fatty acids. Intake was restricted to 90% of ad libitum; DMI was similar among diets (mean 9 kg/d). Total fatty acid intake averaged 170, 500, 506, 525, 489, and 491 g/d for treatments 1 to 6, respectively. Flows of total C16, total C18, and total fatty acids to the duodenum were increased by supplemental fat; flows of total C18 and total fatty acids were greater than their intake for all treatments. Flow of total fatty acids associated with ruminal bacteria accounted for 50 and 17% of the total duodenal fatty acid flow for the control and fat-supplemented diets, respectively. Digestibility of total fatty acids entering the small intestine (74, 71, 62, 39, 53, and 63% for treatments 1 to 6, respectively) was greater for the control diet than for fat-supplemented diets and decreased as either saturation (T < PHT < HT) or esterification (HFA < HTHFA < HT) increased. Digestibilities of fatty acids in the total tract followed similar patterns. Ruminal lipolysis of dietary triglycerides decreased linearly as the degree of saturation of fat sources increased. Small intestinal disappearance of triglycerides (89, 75, 51, 44, 64, and 73% of duodenal flow for treatments 1 to 6, respectively) decreased linearly as either saturation or esterification increased. Flows and digestion of gross energy followed patterns similar to those for fatty acids and triglycerides. Resistance to ruminal and small intestinal lipolysis is a major factor contributing to the poor digestibility of highly saturated triglycerides.  相似文献   

13.
Although dietary n-3 fatty acids have been extensively studied in poultry, they have not yet been prospectively investigated in psittacines, despite potential benefits for preventing and treating atherosclerosis, osteoarthritis, and other chronic disease processes. The objectives of this study were to investigate the incorporation of dietary n-3 fatty acids into red blood cells (RBC) and to determine the effects of supplementation of psittacine diets with fish or flax oil on plasma lipids and lipoproteins in the cockatiel. Adult cockatiels were fed a custom-formulated diet containing either 4% (wt/wt, as-fed) beef tallow (CON), 3% fish oil + 1% tallow (FSH), or 3.5% flax oil + 0.5% tallow (FLX; n = 20 per diet group). Baseline measurements were obtained for RBC fatty acid composition, triacylglycerides (TAG), and cholesterol. After 8 to 13 wk on the study diets, plasma chemistry profiles, lipoprotein density profiles, and RBC fatty acid composition were determined. At 8 wk, total plasma cholesterol was least in FSH birds (P < 0.05) and TAG concentrations were less in FSH birds than FLX birds (P < 0.05). Total n-3 fatty acids, docosahexaenoic acid, docosapentaenoic acid, and eicosapentaenoic acid were markedly greater in the RBC of FSH birds than FLX or CON birds (P < 0.05). Alpha linolenic acid was greatest in FLX (P < 0.05). Initial and final BW, and nonlipid plasma chemistry values did not differ among diet groups. No adverse effects of dietary supplementation of cockatiels with 3.5% flax oil or 3% fish oil were observed during the 13-wk feeding period. Although fish and flax oils provided similar total n-3 PUFA to the diets, fish oil caused greater reductions in cholesterol and TAG, and greater total RBC n-3 incorporation. Thus, dietary modification of psittacine diets with long chain n-3 PUFA from fish oil appears safe and may be beneficial to these long-lived companion birds.  相似文献   

14.
Five Holstein steers (235 kg of BW) fitted with ruminal, duodenal, and ileal cannulas were used in a 5 x 5 Latin square design experiment to determine the effects of supplemental fat source on site and extent of nutrient digestion and ruminal fermentation. Treatments were diets based on steam-flaked corn containing no supplemental fat (control) or 4% (DM basis) supplemental fat as tallow, dried full-fat corn germ (corn germ), corn oil, or flax oil. Fat supplementation decreased (P < 0.08) ruminal starch digestion but increased (P < 0.03) small intestinal starch digestion as a percentage of intake. Feeding corn germ decreased (P < 0.09) ruminal starch digestion and increased (P < 0.03) large intestinal starch digestion compared with steers fed corn oil. Large intestinal starch digestion was less (P < 0.04), and ruminal NDF digestion was greater (P < 0.09) for steers fed tallow compared with steers fed other fat sources. Small intestinal (P < 0.08) and total tract NDF digestibilities were greater (P < 0.02) for steers fed corn germ than for those fed corn oil. Feeding tallow increased total ruminal VFA (P < 0.03) and NH(3) (P < 0.07) concentrations compared with steers fed the other fat sources. Feeding corn germ led to a greater (P < 0.02) rate of ruminal liquid outflow compared with corn oil. A diet x hour interaction (P < 0.04) occurred for ruminal pH, with steers fed corn oil having the greatest ruminal pH 18 h after feeding, without differences at other time points. Fat supplementation increased (P < 0.09) ruminal concentrations of Fusobacterium necrophorum. Duodenal flow of C18:3n-3 was greater (P < 0.01) for steers fed flax oil compared with those fed corn oil. Feeding corn germ led to less (P < 0.01) ruminal biohydrogenation of fatty acids compared with corn oil. Steers fed tallow had greater small intestinal digestibility of C14:0 (P < 0.02) and C16:1 (P < 0.04) than steers fed the other fat sources. Fat supplementation decreased (P < 0.06) small intestinal digestibility of C18:0. Feeding corn germ decreased (P < 0.10) small intestinal digestibility of C18:1 compared with corn oil. It appears that source of supplemental fat can affect the site and extent of fatty acid and nutrient digestion in steers fed diets based on steam-flaked corn.  相似文献   

15.
A 111-d finishing study evaluated animal growth and carcass characteristics using 138 steers (366 kg) in a randomized complete block design with a 2 x 3 factorial arrangement of treatments. The dietary treatments consisted of no supplemental fat or 3.5% tallow or soybean oil soapstock (SS) fed with .6% and .9% dietary Ca. Fat increased DMI (P less than .05) but interacted with Ca level (P less than .05) for gain/feed and ADG. All diets containing fat or .9% Ca were converted more efficiently to gain than the .6% Ca, no supplemental fat diet (P less than .05). The .9% Ca interacted with fat source to decrease gain (P less than .05) and tended to decrease efficiency in the tallow diet but improved efficiency (P less than .05) and tended to improve gain in the no-fat diet. In the SS diet, .9% Ca had no effect on ADG, DMI, or efficiency of gain. Fat addition increased backfat (P less than .10) and interacted with Ca on hot carcass weight, final weight, and dressing percentage (P less than .05). Feeding fat increased the proportion of 18:0 (P less than .02) and decreased the proportion of 16:1 fatty acids (P less than .06) in intermuscular fat. A replicated 3 x 3 Latin square design, using six Holstein steers (349 kg) fed three diets, with no supplemental fat or 3.5% SS or tallow with 1.0% Ca, was used to explore the effects of fat sources when fed with high Ca on digestion and metabolism. Ruminal fluid pH was higher (P less than .10) when steers were fed fat. Adding fat did not affect (P greater than .10) duodenal or ileal pH, VFA proportions or total concentration, or ruminal liquid volume or flow rate. Liquid retention time was shorter and liquid rate of passage was higher (P less than .05) with dietary fat addition. Adding fat did not affect site or extent of starch or DM digestion. There was net synthesis of 16:0, 18:0, and 18:1 fatty acids in the rumen. When steers were fed tallow, synthesis of 16:0 and 18:0 fatty acids in the rumen was lower (P less than .10) than when steers were fed SS. Feeding fat tended to decrease (P = .11) bacterial N flowing at the duodenum but did not affect nonbacterial N or total N. Fat addition seems to affect ruminal kinetics, and the effects may vary with fat source, particularly relative to fatty acid synthesis and digestion.  相似文献   

16.
A balance trial was conducted to titrate the effects of tallow on the energy metabolism of wethers fed barley finishing diets. Six dietary levels of tallow (0, 2, 4, 6, 8, or 10%) in a barley finishing diet were fed to six crossbred wethers (35+/-1.1 kg) in a randomized complete block design. Diets were 73% barley, 10% tallow and(or) bentonite, 10% alfalfa pellets, and 7% supplement. There was no effect of tallow level on OM intake (1,103.1+/-51 g/d), OM digestibility (84+/-0.9%), GE digestibility (83+/-1.1%), or cell solubles digestibility (84.2+/-1.2%). The level of tallow quadratically decreased ADF digestibility (P < 0.05), methane emissions, and methane energy as a percentage of GE P < 0.01). There were linear increases in dietary GE (megacalories per kilogram of OM [P < 0.01]), dietary DE (megacalories per kilogram of OM [P < 0.05]), and dietary ME (megacalories per kilogram of OM [P < 0.01]), as dietary tallow increased. Numbers of ruminal protozoa (Entodinium spp. and Polyplastron sp.) decreased linearly (P < 0.05) with increased level of tallow. The energy value of tallow (calculated by difference) was low. The total-tract fatty acid digestibility of tallow was calculated by linear regression, without intercept, after accounting for the fatty acids digested from the base diet (0% tallow fed to a wether in a period). Fatty acids of the same carbon length were pooled for the regression analysis. All linear regressions were significant (P < 0.10) indicating no effect of tallow level on fatty acid digestibility. Lauric acid had low digestibility. The high digestibility of all C16 (89%) and C18 (104%) fatty acids suggests an effect of tallow on endogenous and microbial fatty acid excretion. Fatty acid digestibility was probably a minor contributor to the low energy content of tallow, calculated by difference, in these diets.  相似文献   

17.
Two experiments were conducted with Polypay ewes nursing twin lambs to evaluate the effects of supplementing fat (calcium salts of palm oil fatty acids or hydrogenated tallow) on ewe lactation. In Exp. 1, ewes were fed a 52% concentrate:48% hay-based diet (as-fed basis) consisting of alfalfa hay (n = 4), endophyte-free fescue hay (n = 4), or fescue hay with 3.7% fatty acids (n = 4) from d 4 to 56 of lactation. In Exp. 2, ewes were fed similar diets that had endophyte-free fescue hay (n = 6), fescue hay with 3.7% fatty acids (n = 5), or fescue hay with 3.1% tallow (n = 6) from d 14 before lambing until d 57 of lactation. Diet formulations with supplemental fat were more nutrient dense, and treatments were fed to meet ewe nutrient requirements; this caused diets with added fat to be offered at 10 and 17% lower rates than unsupplemented diets in Exp. 1 and 2, respectively. Lambs were maintained to consume only ewe milk. Ewe milk production and composition were determined using a portable milking machine following a 3-h separation from lambs. In Exp. 1, milk fat content was increased (P < 0.01) when ewes consumed fescue hay with fatty acids vs. the fescue hay diet (11.4 vs. 8.3%). Ewes fed fescue hay with fatty acids lost the most (P < 0.05) weight over lactation (-8.6 kg) compared with ewes fed the alfalfa hay (-2.4 kg) and fescue hay (-3.8 kg) diets. Other milk measures, lamb gain, and production efficiencies were not changed. In Exp. 2, ewes supplemented with fatty acids produced more (P < 0.05) milk fat than those fed tallow (290 vs. 210 g/d). The proportion of synthesized milk fat 14:0 was decreased (P < 0.01), but the percentage of incorporated 16:0 increased (P < 0.05) when fatty acids were fed. Dietary fat digestibility by ewes was increased (P < 0.01) by fatty acid supplementation but decreased (P < 0.01) when tallow was added. Although ewe weight measures were not changed in Exp. 2, twin lamb gain per ewe organic matter intake was most efficient (P < 0.05) when ewes were supplemented with fatty acids. Results suggest that feeding hydrogenated tallow decreased nutrient availability for ewe milk fat production. A complete diet based on endophyte-free fescue hay can replace a traditional alfalfa hay diet, whereas supplementing with the calcium salts of palm oil fatty acids may be more feasible when energy is limiting during ewe lactation.  相似文献   

18.
An experiment was conducted to determine the effects of Cu and soybean oil (SBO) supplementation on ruminal and tissue lipid metabolism and carcass characteristics in finishing steers. Sixty Angus steers (369.0 +/- 10.1 kg) were stratified by weight and randomly assigned to treatments in a 2 x 2 factorial arrangement, with factors being 0 or 20 mg of supplemental Cu/kg DM from Cu sulfate and 0 or 4% SBO. Steers were fed a high-concentrate basal diet that contained 5.3 mg Cu/kg DM. Average daily gain and feed intake were reduced (P < 0.01) by SBO but were not affected by Cu. Gain:feed ratio was not affected by treatment. Liver Cu concentrations were higher (P < 0.01) in steers receiving supplemental Cu and lower (P < 0.04) in SBO-supplemented steers. Copper supplementation tended to reduce (P < 0.12) and SBO supplementation tended to increase (P < 0.11) serum cholesterol concentrations. Backfat depth was reduced (P < 0.10) by Cu and SBO supplementation. Marbling scores and longissimus muscle lipid content were not affected by Cu supplementation; however, SBO supplementation reduced (P < 0.01) marbling scores. Longissimus muscle polyunsaturated fatty acids tended to be increased (P < 0.14) in Cu-supplemented steers. Longissimus muscle C18-conjugated dienes and the 18:1 trans isomer were increased (P < 0.05) in SBO-supplemented steers. Ruminal fluid 18:3 was increased (P < 0.05) and the 18:1 trans isomer was decreased (P < 0.05) in Cu-supplemented steers. These results indicate that as little as 20 mg of supplemental Cu/kg DM can reduce backfat and may alter lipid metabolism in steers fed high-concentrate diets.  相似文献   

19.
A 120-d finishing study utilizing 318 heifers (342 kg initial BW) was conducted to examine effects of ruminally protected choline (RPC) in diets containing graded concentrations of tallow. Heifers were blocked according to previous nutrition (full-fed or limit-fed) and allotted to 24 pens containing 11 to 15 heifers. Two pens, one within each block, were assigned to each of 12 factorially arranged treatments including dietary tallow (0, 2, or 4%) and supplemental RPC (0, 20, 40, or 60 g of product daily, estimated to supply 0, 5, 10, or 15 g/d choline postruminally). Heifers were implanted with Revalor-H and fed a finishing diet based on steam-flaked and dry-rolled corn (12.5% CP, 8% alfalfa on DM basis). Dry matter intake decreased (P < 0.10) by 5.4% when tallow was increased from 0 to 4% but was not affected by RPC. Heifers receiving 4% tallow had 7.3% lower gains than those receiving none (P < 0.10). Supplementation of RPC increased (P < 0.10) ADG, with 20 g/d resulting in an 8.6% increase. Similarly, gain efficiency improved (P < 0.10) by 7.6% with addition of 20 g/d RPC. Yield grade and kidney, pelvic, and heart fat both increased linearly (P < 0.10) with fat supplementation. The percentage of carcasses grading USDA Choice was not affected by intermediate levels of RPC but decreased with the highest level (60 g/d). Dressing percentage, hot carcass weight, marbling, and 12th-rib fat thickness were not affected significantly by either tallow or RPC. On d 90, jugular blood was collected from all heifers at 2 h postfeeding. Plasma urea and serum insulin concentrations were not affected by either tallow or RPC. Dietary tallow linearly increased (P < 0.10) NEFA, cholesterol, triglyceride, and total amino acid concentrations. Choline supplementation led to quadratic responses for total amino acids (P < 0.10), with concentrations being greatest for intermediate levels of RPC. Moderate levels of supplemental RPC improved growth performance of finishing cattle without negatively affecting carcass characteristics. Optimum performance was achieved with 20 g of product daily.  相似文献   

20.
The experiment investigated the digestion of lipids from different forage silages in beef steers. Six Hereford x Friesian steers prepared with rumen and duodenal cannulas were given ad libitum access to a high-sugar grass silage, control grass silage, red clover silage, or mixtures of the red clover and each of the grass silages (50:50, DM basis). The experiment was conducted as an incomplete 5 x 5 Latin square, with an additional randomly repeated sequence. Total fatty acid and C18:3n-3 concentrations were greater (P < 0.05) for the high-sugar grass silage than the control grass silage or the red clover silage. Dry matter and total fatty acid intake were less (P < 0.05) for steers fed the control grass silage than for steers fed the other diets. Duodenal flow of C18:3n-3 was greater (P < 0.05), and flows of C18:0 and total C18:1 trans were less (P < 0.05), for the red clover silage compared with the 2 grass silage diets, with the mixtures intermediate. These results were supported by a reduction (P < 0.05) in biohydrogenation of C18:3n-3 for the red clover silage, with the mixtures again being intermediate. Flows of total branched- and odd-chain fatty acids were greater (P < 0.05) for the high-sugar grass silage diet, possibly as a result of greater microbial flow, because these fatty acids are associated with bacterial lipid. Duodenal flows of the chlorophyll metabolite, phytanic acid, were greater (P < 0.05) for animals fed the high-sugar grass silage treatments compared with the other treatments. These results confirm the potential for modifying the fatty acid composition of ruminant products by feeding red clover silage.  相似文献   

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