Effect of rotating monensin plus tylosin and lasalocid on performance, ruminal fermentation, and site and extent of digestion in feedlot cattle.

Two trials were conducted to evaluate the effects of ionophore rotation programs on performance and digestion by feedlot cattle. A 90% concentrate diet was fed with treatments of no ionophore (C), 33 mg lasalocid/kg diet daily (L), 29 mg monensin plus 11 mg tylosin/kg diet daily (MT), and daily (D) and weekly (W) rotation of L and MT. In Trial 1, feedlot performance of 200 crossbred steers (average initial BW 296 kg) was evaluated during a 133-d period. In Trial 2, four crossbred steers (average initial BW 376 kg) fitted with ruminal, duodenal and ileal cannulas were used in a 4 x 4 Latin square design to evaluate treatment effects (excluding W) on ruminal fermentation and site and extent of digestion. In Trial 1, daily rotation of L and MT improved (P less than .10) feed:gain ratio compared with other treatment groups, but daily feed intake did not differ (P greater than .10) among treatments. Daily gain was greater (P less than .10) for steers fed D than for those fed C or MT, but not different from that of steers fed L or W. Carcass measurements did not differ (P greater than .10) among treatments. In Trial 2, ruminal molar proportions of butyrate and valerate were decreased (P less than .07) by MT and D compared with C and L. Proportions of other VFA, ammonia concentrations and ruminal pH did not differ among treatments. Ionophore treatments did not affect site or extent of digestion of OM, starch or N; no differences among treatments were observed for efficiency of microbial protein synthesis. Although daily rotation of L and MT improved performance of growing-finishing feedlot steers, this improvement was not attributable to alterations in ruminal fermentation, or in site or extent of nutrient digestion.

Nutrition and management of stressed beef calves. An update.

In an earlier report in the Veterinary Clinics: Large Animal Practice, the author discussed some basic principles upon which receiving programs for stressed calves should be based. Additional information has been developed in some of the areas covered in that report and in certain other areas. It is the purpose of this article to discuss some of this new information, after a brief review of the basics.

Effects of receiving and growing diets on compensatory gains of stressed calves.

Three hundred seventy-seven male stocker calves were used to study the effects of three receiving diets, two growing-finishing diets and two levels of shipping shrink on compensatory gains during the post-receiving feeding period. Calves received on a 75% concentrate diet gained 19 kg more during the first 42 d than those received on hay plus .91 kg daily of protein supplement (P less than .01). Calves received on hay plus protein supplement gained 11 kg more than the calves received on hay alone during the same period (P less than .01). When calves were fed an 85% concentrate diet throughout finishing, there was no difference in the rate of compensatory gain made by calves fed hay alone or hay plus protein supplement. Neither of the latter two groups completely compensated for the slow rates of gain made during receiving. When calves were fed a 50% concentrate growing diet from the end of the receiving period to a body weight of 272 kg then finished on an 85% concentrate diet, those received on hay alone lacked only 1 kg of compensating fully for the low gains of the receiving period. However, this procedure had no effect on the compensatory gains of those received on hay plus protein supplement. High-shrink calves received on hay alone or hay plus protein never compensated fully for the low gains made in the receiving period. However, with low-shrink calves, those received on hay alone fully compensated for the low gains of the receiving period and those received on hay plus protein lacked only 2 kg of making full compensation.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of steam-flaked, steamed-whole or whole shelled corn on performance and digestion in beef steers.

Three trials were conducted to evaluate finishing diets containing 67% steam-flaked corn (SFC), steamed-whole corn (SWC) or whole corn (WC). In a feeding trial, steers fed SWC consumed more (P less than .05) dry matter per day (7.6 kg) than those fed WC (7.0 kg) or SFC (6.7 kg). Average daily gain was greater (P less than .05) for steers fed SFC (1.33 kg) and SWC (1.31 kg) than for those fed WC (1.25 kg), and feed efficiency was better (P less than .05) for steers fed SFC (5.06 kg dry matter/kg gain) than for those fed WC (5.62) and SWC (5.79). Carcass characteristics were not different among the three groups. In a digestion trial, method of corn processing did not affect digestibility of dry matter and crude protein. Starch digestibility was greater (P less than .05) for SFC (99.1%) than for SWC (93.8%) and WC (93.0%). There were no differences in nitrogen (N) intake or fecal N among the three diets; however, urinary N was less (P less than .05) for SWC (19 g/d) than for SFC (27 g/d) and WC (32 g/d), and N retention was higher (P less than .05) for the SWC diet. In vitro dry matter digestibility of the SFC diet was higher (P less than .05) than for WC at 4 and 8 h of incubation and higher (P less than .05) than the SWC diet at 8, 12 and 24 h of incubation. In vitro gas production after 6 h was greater (P less than .05) for SFC than for SWC grain, which was greater (P less than .05) than WC.(ABSTRACT TRUNCATED AT 250 WORDS)

Mass medication in reducing shipping fever-bovine respiratory disease complex in highly stressed calves.

One thousand and eighty-five newly received, stressed calves were used in studies to determine the effectiveness of certain mass medication procedures for reducing morbidity from shipping fever-bovine respiratory disease complex. In two experiments, im injections of oxytetracycline at 11 mg/kg body wt for 3 successive days reduced treatment days/calf purchased 21 (P less then .05) and 31% (P less than .05). Oral administration of 150 mg of sulfadimethoxine/kg body wt reduced treatment days/calf purchased 20 (P less than .05) and 54% (P less than .05) in the same two experiments. When sulfadimethoxine followed oxytetracycline on the third injection day an 81% reduction in treatment days/calf purchased was obtained, indicating an additive effect of the two drugs. The use of long acting oxytetracycline and sustained release sulfadimethoxine at the time of processing resulted in a 90% reduction in treatment days/calf purchased (P less than .01) and required only one handling of the calves for mass medication purposes.

Millet and alfalfa hays alone and in combination with high-energy diet for receiving stressed calves.

Calves subjected to stresses of weaning, marketing, shipping and processing ate more feed, gained more weight and gained more efficiently when fed a 75% concentrate receiving diet, alone or with free choice hay, than when fed hay alone (P less than .01). Diets with greater bulk or lower energy densities did not promote higher feed intake in these stressed calves, as would be the case in unstressed animals. No differences due to receiving diets were observed in number of calves treated, days treated per sick calf, death loss or relapses. There was a trend (P less than .1) for calves on hay diets to have fewer total sick days than those fed a 75% concentrate diet alone or with free choice hay. Feed intake, weight gains and conversion of feed to gain for calves on alfalfa hay alone were superior (P less than .05) to the corresponding measures for calves on millet hay alone. Both hays fed alone were inferior (P less than .01) to a 75% concentrate diet alone or in combination with either hay in promoting weight gains and conversion of feed to gain. Gastrointestinal tract fill estimated from apparent and predicted gains amounted to 93 and 76% of apparent gains for calves fed millet or alfalfa hay respectively, but only 58% or less for those fed diets containing the 75% concentrate milled feed. Growing lambs were in negative N balance when fed millet hay alone but retained approximately 15% of N intake when fed diets containing the 75% concentrate milled feed. N retention on alfalfa hay alone was intermediate. The data indicate net tissue growth in calves fed millet hay alone is near zero during a 28-day receiving period. No differences were noted between calves receiving grubicide as a dip and those given grubicide as a pour on.

Effects of dietary energy, free choice alfalfa hay and mass medication on calves subjected to marketing and shipping stresses.

Five-hundred and fourteen calves subjected to the stresses of marketing and shipping from Florida to New Mexico were used to study performance after arrival at the feedlot. Flaked milo diets containing 50 and 75% concentrates promoted more rapid recovery of purchase weight and more efficient gains than a diet containing 25% concentrates. Free-choice alfalfa hay with the flaked milo diets reduced death loss, number of calves requiring medication and number of treatments per medicated calf. A 3-day mass medication with oxytetracycline injected intramuscularly at 11 mg/kg body weight reduced death loss and number of calves requiring subsequent medication. Calves requiring subsequent medication, however, needed more treatments than control calves. Dry matter and energy digestion determined with lambs increased with concentrate level but decreased with addition of alfalfa hay. New energy intake was highest for the 50% concentrate diet during the first week and for the 75% concentrate diet during the next 3 weeks of the 4-week receiving period.

Metabolic and cellular profile testing in calves under feedlot conditions: minerals, electrolytes, and biochemical components--reference values.

Blood serum samples were obtained from 114 crossbred calves on a feed trial under feedlot conditions at the end of a 56-day feeding period. Average values for 19 blood components were determined. The effects of the 3 trial rations and 2 electrolyte treatments were analyzed. Except for inorganic phosphates, urea nitrogen, cholesterol, glucose, alanine aminotransferase, and alkaline phosphatase most mean values were similar to those in dairy cattle. Urea nitrogen values differed significantly (P less than 0.05) in animals fed different rations apparently reflecting the crude protein content of each ration. The mean values presented can be used as base-line data for comparison with other similar studies or with values from diseased animals.

Metabolic and cellular profile testing in calves under feedlot conditions: minerals, electrolytes and biochemical components--changes over time in feedlot.

The concentration of 19 mineral, electrolyte, and biochemical components in blood serum of 114 calves under feedlot conditions were measured or calculated over a 58-day period (2 days before and 56 days during a feed trail). The purpose was to evaluate the variability in the concentration of these components over time. The blood was collected on 7 sampling dates and analyzed on the day following sampling. Generally, the serum concentrations of the components that were measured varied considerably over the first 3 weeks of the feeding period and then had a tendency to level off during the 2nd part of that period.

Metabolic and cellular profile testing in calves uncer feedlot conditions: blood cellular components--reference values and changes over time in feedlot.

The cellular components of the blood of 114 calves were measured under feedlot conditions. The results suggest that certain cellular components of the blood of a group of crossbred feedlot-type calves which are homogeneous only with regard to weight are reasonably uniform. More specifically, all red blood cell components have coefficients of variation of less than 10%. The white blood cell counts underwent drastic changes over the first 2 sampling dates, ie, before and after transport and processing of the calves. Later, in the feeding period, the cell counts readjusted to more stable levels. The results were compared with such values obtained from dairy cattle. The total erythrocyte count, total leukocyte count, and red blood cell components were found to be slightly higher in these feedlot calves than in dairy cattle. The difference might partly be due to age. The mean values reported can be used as a base for comparison with values obtained from other such studies or from studies of disease processes in cattle under feedlot conditions (or both).