T.W. White

Influence of dietary carnitine in growing sheep fed diets containing non-protein nitrogen.

The influence of supplemental L-carnitine was investigated in growing sheep fed rations containing non-protein nitrogen (NPN). The experiment was conducted as a randomized block design with a 2x2 factorial arrangement of treatments. Lambs (77.4kg BW, n=24) were fed a total mixed ration (12.1-13.6% CP) with two levels of L-carnitine (0 or 250ppm) and two levels of NPN (urea contributing 0 or 50% of total dietary N) for a 50-day period. Jugular blood samples were collected at 0, 1, and 3h post-feeding, and ruminal fluid samples were collected at 1h post-feeding, during days 1, 8, 29, and 50 of the experiment. Average daily gain (121 versus 214g) was lower (P<0.0001) in lambs fed the NPN diets. Lambs consuming diets containing NPN had higher (P<0.0001) ruminal fluid pH (6.6 versus 5.9), ruminal ammonia N (4.8 versus 2.8mmol/l), and plasma ammonia N (177.1 versus 49.5µmol/l) than lambs not fed NPN. Additionally, lambs fed the NPN diets had lower plasma urea N (14.5 versus 17.5mmol/l; P<0.003) and thyroxine (T(4)) concentrations (65.8 versus 78.4ng/ml; P<0.02), and lower T(4):triiodothyronine (T(3)) ratio (37.9 versus 43.9; P<0.02). Plasma glucose concentrations were higher (P<0.05) in lambs fed L-carnitine (3.83 versus 3.70mmol/l). Two oral urea load tests (OULT 1 and OULT 2) were conducted during the 50-day trial. Urea solutions (0.835g/kg(0.75) BW) were administered as oral drenches. During the OULT 1 (day 10), plasma ammonia N and glucose concentrations were highest (P<0.0001) in the lambs fed NPN with L-carnitine compared with lambs fed control, L-carnitine, and NPN diets. During the OULT 2 (day 50), plasma ammonia N was highest (P<0.0001) in the NPN and NPN with L-carnitine groups compared with the control and L-carnitine groups. Plasma glucose was lowest (P<0.04) in the NPN with L-carnitine group compared with the NPN and L-carnitine groups, but did not differ (P>0.10) from the control group. Plasma urea N levels in both OULT 1 and OULT 2 were lower (P<0.0001) in the NPN and NPN with L-carnitine groups compared with the control and L-carnitine groups. In the present experiment, production and plasma criteria were affected by NPN incorporation in the diets. Production criteria were not affected by inclusion of L-carnitine in the diet, however, L-carnitine reduced experimentally induced hyperammonemia by day 50 of the trial.

Influence of Urea Alone or Combined with Fish Solubles, Fish Meal, or Feather Meal in Liquid Supplement with and Without L-Carnitine on Performance and Ruminal and Metabolic Parameters of Weanling Calves

Using growing calves (n = 368) grazing mature forage in three 84-d experiments, one objective was to compare the effects of feeding molasses-based liquid supplements containing urea (U) alone or combined with fish solubles (FS), fish meal (FM), or feather meal (FE) on performance, and blood metabolites. Another objective was to evaluate the effects on these criteria of adding carnitine to these supplements to provide 1 g·h−1·d−1 L-carnitine. Including FM or FE in the mixture improved (P<0.05) supplement consumption in two experiments and improved growth rate in all experiments. Carnitine improved the growth rate when U was the only protein source, but reduced growth rate when FM was included in the liquid supplement (P<0.05). During the growth phase, plasma ammonia N (PAN) was higher (P<0.05) when U was the only protein source as compared with FM or FE. Carnitine did not influence these metabolic parameters. During the metabolic phase of each experiment, calves similar to those used in the growth phase were dosed via stomach tube with 3 g liquid supplement/kg BW. Ruminal and blood samples were collected at 0, 0.5, 1, 2, and 4 h after dosing. Ruminal ammonia N, PAN, and plasma urea N (PUN) concentrations were higher (P<0.05) when calves were dosed with U or FS supplement than when dosed with FM or FE supplements. Calves dosed with liquid supplement containing carnitine had lower (P<0.05) concentrations of ruminal ammonia N and PAN. Carnitine reduced (P<0.05) PUN in one experiment and increased (P<0.05) PUN in another. Branched-chain volatile fatty acids were increased (P<0.05) by dosing with FS or FM supplements. Including ruminally undegradable protein sources (FM or FE) in liquid supplement improved intake and performance and was related to reduced ruminal ammonia N, PAN, and PUN. Carnitine fed in liquid supplement also reduced ruminal ammonia N and PAN concentrations.

Influence of L-Carnitine on Performance and Ruminal and Blood Metabolites of Grazing Calves and Finishing Lambs12

Three experiments were conducted to study the influence of level and type of L-carnitine (LC) on performance and rumiasl and plasma metabolites of weanling calves and finishing lambs. Weanling calves (84) grazing dormant dallisgrass-bermudagrass forage were fed a 20% CP supplement to provide 0, 0.5, 1, or 2 g of ruminally unprotected (RUP) LC per calf daily in Exp. 1. There was a linear increase (P=0.01) and cubic response (P=0.03) to RUP LC in growth rate and quadratic changes (P=0.01) in plasma ammonia N (PAN) and plasma urea N (PUN). In Exp. 2, 32 lambs were individually fed 14% CP diets containing 0, 50, 100, or 200 ppm RUP LC or ruminally protected (RP) LC in a 2 × 4 arrangement of treatments. Lambs gained BW faster (P=0.03) and more efficiently (P=0.07) as the LC level increased to 100 ppm and then declined at 200 ppm (quadratic response). Longissimus area decreased (P=0.03), and fat cover tended (P=0.15) to decline, at 50 and 100 ppm LC and increased at 200 ppm (linear and quadratic response). Ruminal ammonia N levels were reduced at 50 ppm LC but increased at greater LC levels (linear, quadratic, and cubic response, P=0.02). Plasma carnitine concentrations increased (P=0.01) as the dietary level of LC increased. Protected LC was more effective than RUP LC in increasing growth rate (P=0.06) and reducing PAN (P=0.1). In Exp. 3, 16 wether and 16 ewe lambs were individually fed corn-based or soybean hull-based diets with 0 or 100 ppm RP LC in a 2 × 2 arrangement of treatments. Lambs fed RP LC gained BW faster and more efficiently (P=0.04) than lambs that were not fed LC. Lambs fed corn-based and soybean hull-based diets responded similarly to RP LC; however, performance was greater (P=0.03) for lambs fed the corn-based diet. Gender of lambs did not influence the response to diet or RP LC. Supplementing the diet with 100 ppm RP LC reduced (P=0.01) ruminal pH and ammonia N. Plasma carnitine concentrations were increased (P=0.01), and PAN was decreased (P=0.04) by feeding 100 ppm RP LC. Ruminnaly unprotected and RP LC were effective in improving growth rate in ruminants; the latter appeared to be more effective in finishing lambs. L-carnitine reduced ruminal ammonia N and plasma glucose and, in some cases, PAN and PUN.

Effects of Fish Meal and Sodium Bentonite on Performance, and Ruminal and Blood Characteristics of Kids Fed Concentrate or Forage Diets,

Twenty-four wether and 24 doe crossbred kids were used to evaluate the effect of fish meal (FM) and sodium bentonite (NaB) on growth, and ruminal and blood metabolites. Six treatments were: four isonitrogenous (13.5% CP) diets (0% FM and 0% NaB; 0% FM and 0.75% NaB; 3% FM and 0% NaB; or 3% FM and 0.75% NaB) fed to confined kids, and the 0% FM and 0% NaB or 3% FM and 0% NaB diets fed to grazing kids as supplement. Diets were based on corn, soybean meal, and cottonseed hulls. Data were analyzed as two independent 2 × 2 factorial arrangements. The first analysis compared the four diets fed in confinement. The second analysis compared 0 or 3% FM supplemented diets fed in confinement to the same diets fed as supplements to grazing kids. Grazing kids were allowed 8 h daily grazing time on pasture. After grazing, kids were penned individually and allowed access to their respective supplements for 1 h. A FM × NaB interaction (P<0.02) occurred for average daily gain (ADG) where FM improved ADG in the absence of NaB but not in the presence of NaB. There were similar trends noted for DMI and gain per feed (g/kg DMI). Growth rates of confined and grazed kids were similar and both were improved (P<0.01) by including FM in the supplement. Ruminal pH was increased and total VFA decreased by feeding FM to confined kids (P<0.01). Kids that were supplemented after grazing had higher ruminal pH, acetate, isobutyrate, butyrate, and isovalerate and lower propionate levels than kids in confinement. Dietary FM had no effect on blood metabolites of confined or grazed kids. This research suggests that replacing a portion of dietary soybean meal protein with fish meal protein in the absence of NaB improves the growth rate of kids. Grazing kids that are properly supplemented gain as fast on 40% less feed as kids fed complete diets in confinement.

Goat Preference for Concentrates or Forages Is Influenced by Physical and Chemical Characteristics of the Feed1

Two trials were conducted to determine easily measured physical and chemical characteristics that affected voluntary intake of forages or concentrates by goat kids in production settings. In Trial 1, goat kids were offered two concentrates simultaneously, and intake of each was recorded. Additionally, the time required by kids to consume 100 g of DM from each supplement was recorded. In Trial 2, kids were offered two forages for 3 h, and intake of each was recorded. Kids preferred pelleted supplements over those offered as a meal or liquid. They also preferred supplements offered as a meal over those offered as a liquid. Kids preferred supplements based on either corn or soybean meal over those based on fishmeal or molasses. Kid preference for concentrate supplements was highly related to time required for consumption of 100 g of DM. Kids consumed more DM from stored forages than from fresh forages. When offered fresh forages, kids consumed more DM from fresh cereal grain forages than from Brassica spp. or clovers. Kids also consumed more DM from Brassica spp. than from clovers. Consumption of forages by kids was positively related to DM content of the forages. Goats consumed concentrates and forages to maximize the nutrient intake in the allotted amount of time.

Influence of Energy and Protein Supplementation on Growth Rate, Empty Body Composition and Ruminal and Blood Metabolites of Goat Kids Fed Hay Diets1

A comparative slaughter experiment was conducted with 28 Spanish kids (BW = 20.6 kg) fed a hay-based diet to determine the effects of supplemental energy and protein on growth rate, body composition, and ruminal and blood metabolites. After 84 d, kids were harvested, digesta contents removed and empty body weighed and ground. Samples were freeze-dried and analyzed for DM, CP, ether extract, ash, and gross energy. All kids had increased BW gains. However, unsupplemented kids lost empty BW and weight of all body components except ash. Kids supplemented with energy or protein increased (P<0.05) empty BW, body water, protein, fat, ash, and gross energy when compared with unsupplemented kids. The percentages of body water and ash decreased (P<0.05) when supplemental energy or protein was fed. The percentage of body protein was reduced (P<0.05) by supplemental energy and unaffected (P=0.81) by supplemental protein. Supplemental energy reduced (P<0.05) ruminal acetate and increased (P<0.05) propionate and butyrate. Supplemental protein increased (P<0.05) concentrations of ruminal ammonia N, plasma urea N, and all ruminal volatile fatty acids. Regression equations suggest that intake of 144 kcal of ME and 6.0 g of CP per kilogram of empty BW0.75 are necessary to maintain empty BW.

Influence of Urea Alone or Combined with Fish Meal and Solubles in Liquid Supplements on Performance of Grazing Cow-Calf Pairs

Experiments were conducted for 84 d, beginning on July 1, with cow-calf pairs grazing summer grass to determine the effects of feeding molasses containing urea or urea, fish solubles, and fish meal on BW gains, milk production, and blood metabolites. The four treatments based on a 16% CP urea-molasses mixture were no supplement, 97.8% base mixture plus 2.2% urea for cows and calves, 80% base mixture plus 10% fish solubles and 10% fish meal for cows and calves, and the supplement with fish solubles and fish meal as a creep feed for calves. The mixture contained 23% CP as fed. In Exp. 1, 60 crossbred cows with Angus-sired calves were allotted according to sex and birth date to 12, 2-ha pastures. Three pastures each with five cow-calf pairs were assigned to each treatment. In Exp. 2, 48 Hereford X Brahman F1 cows with Angus- or Belgian Blue-sired calves were allotted as in Exp. 1 to 24, 1-ha Alicia bermudagrass pastures. Three pastures with two cow-calf pairs were assigned to each treatment for each sire breed of calf. Cows were machine-milked, and jugular blood samples were collected initially and on d 28 and 56. Cows and calves were weighed, and cows were condition-scored after a 16-h shrink at the beginning and end of both experiments. Both supplements were consumed at similar levels (1.75 kg/d) by cow-calf pairs in both experiments. Cows in Exp. 1 and calves in both experiments gained more (P<0.05) BW when cow-calf pairs had access to the supplement containing fish solubles and fish meal. Milk yield was numerically higher on d 28 (P<0.18) and d 56 (P<0.11) when cows received fish solubles and fish meal in the supplement. The decline in milk yield from initial milking tended to be less (P<0.10) on d 28 and was less (P<0.05) on d 56 when cows received this supplement. Plasma ammonia N concentrations were higher (P<0.05) when cows were fed supplement containing only urea, and both supplements increased (P<0.05) plasma urea N when compared with no supplement. Supplements containing molasses, urea, fish solubles, and fish meal appear beneficial for cow-calf pairs grazing summer forage.

Effects of Dietary Acetate and Propionate on Nutrient Digestibility, Ruminal Characteristics, and Performance by Steers Fed Diets Containing All-Concentrate or 20% Roughage1

Abstract Four experiments were conducted to evaluate the effects of dietary volatile fatty acids (VFA) on nutrient digestibility, ruminal characteristics, and growth performance by finishing steers. Diets were based on sorghum grain in Exp. 1 and 2, and corn in Exp. 3 and 4. Experiment 1 was a digestibility study with eight steers used in two 4 x 4 latin square arrangements of steers and diets. Diets in the first square were all-concentrate (C) with 1 or 2% acetate (A) or 2% propionate (P), and diets in the second square were 20% rice straw (RS) with 1 or 2% A or 2% P. In Exp. 2, steers (four per treatment) were individually fed C or RS basal diets with 1.72% A or 5.00% P added to the C diet, and 1.14% A or 3.33% P added to the RS diet based on expected intake. In Exp. 3 and 4, C diets were diluted with 1.65 or 0.55% A, respectively. These diets were further diluted with 20% rice hulls (RH) in Exp. 3, and 20% RH and 20% RS in Exp. 4. The C diet was also diluted with 20% RS in Exp. 3 and considered a positive control. Adding A, P, or RS to C diet based on sorghum grain had no effect (P>0.10) on energy digestibility or N retention. In Exp. 2, P reduced (P

Effect of Nutrient Restriction and Realimentation on Growth and Metabolic Responses of Shorn Suffolk, Gulf Coast Native, and Crossbred Lambs1

Growth and plasma hormone and metabolite levels were used to compare the effects of nutrient restriction and realimentation on six Suffolk (S), six Gulf Coast Native, (G) and seven S×G crossbred lambs. Shorn lambs were individually fed a 10% CP diet consisting of 20% cottonseed hulls, 74% ground corn, 1% soybean meal, 3% fish meal, 1.1% oyster shell flour, 0.5% urea, and 0.4% trace mineral salt and vitamin A, D, and E mixture. Lambs were fed at 110% of maintenance, 200% of maintenance, or had ad libitum access to feed during periods 1, 2, and 3, respectively. Each period was 28 d in length. Breed did not affect (P>0.25) weight change during nutrient restriction or realimentation. All lambs lost weight during the first period. The calculated NEm of weight loss and 10% feed intake above maintenance suggests an 88% increase in maintenance energy requirement at 11.6 ± 0.9°C average temperature. Similar shorn G lambs maintained weight even though fed at 200% of maintenance, suggesting a 99% increase in NEm. Plasma cortisol was lower (P<0.05) and thyroxine higher (P<0.05) in S than G or S×G lambs. Plasma cortisol levels were stable from d 14 through 42 declining to d 70 and increasing on d 84. Plasma thyroxine, urea N, and NEFA concentrations followed a similar pattern. There were differences between breed in plasma hormone levels but not plasma metabolite or weight change. Maintenance energy requirement of shorn lambs was increased.