Outcomes after treatment of nonsevere gram-negative clinical mastitis with ceftiofur hydrochloride for 2 or 5 days compared with negative control.

A study was conducted at 3 commercial dairies in California to compare outcomes of treating nonsevere (mild and moderate) gram-negative (GN) clinical mastitis (CM) with intramammary (IMM) ceftiofur HCl (125 mg of ceftiofur HCl per tube) in either 2-d (SP2) or 5-d (SP5) treatment programs compared with nontreatment (CON). In addition, we contrasted results from cases classified as mild and moderate. Four hundred fifteen cases were included in the final dataset, including 135 CON, 133 SP2, and 147 SP5. Milk from quarters with CM was sampled for on-farm culture (OFC) to differentiate gram-positive (GP) and GN bacteria, with results known within 24 h. Those with GN infections were randomly assigned to experimental groups, while those with GP, mixed infections, and contaminated samples did not continue in the study and received standard farm therapy. For cows with GN infections, a sample was submitted for MALDI-TOF assay. Only nonsevere cases were enrolled, and all quarters yielded monocultures of GN species. Clinical scores were obtained 0, 1, 2, 3, 4, 5, 14, 21, and 28 ± 3 d relative to enrollment. Milk samples were collected from quarters 14, 21, and 28 ± 3 d after enrollment, and submitted for routine culture and, when appropriate, submitted to MALDI-TOF evaluation. For many response criteria, there were significant interactions between treatments and CM severity scores at the time of enrollment, with effectiveness of ceftiofur HCl treatment being more beneficial compared with CON as mastitis clinical severity increased. While most treatment responses were significant for animals with mild or moderate GN mastitis, the largest responses were noted among cows with moderate CM cases.

Growth promoting hormonal implant pellets coated with a polymeric, porous film promote weight gain by grazing beef heifers and steers for up to 200 days.

Two studies evaluated growth promoting effects of implant pellets (IP), each containing 3.5 mg estradiol benzoate (EB) and 25 mg trenbolone acetate (TBA), to which a polymeric, porous coating was applied. Trial 1 evaluated performance of heifers (n = 70/treatment, initial BW = 188 ± 2.2 kg) and steers (n = 70/treatment, initial BW = 194 ± 2.2 kg) implanted subcutaneously in the ear with 0 (SC), 2 (2IP), 4 (4IP), or 6 (6IP) pellets that delivered EB/TBA (mg/mg) doses of 0/0, 7/50, 14/100, and 21/150, respectively, over grazing periods of 202 d (heifers) or 203 d (steers). Animals received experimental treatments on d 0 and over the grazing period were managed as single groups by sex in a rotational grazing system. When pasture forage availability became limited, cattle were supplemented with preserved forage but not concentrate supplements. Weight gains by heifers treated with 2IP, 4IP, and 6IP were greater (P < 0.05) than SC heifers but not different from each other. Weight gains by steers treated with 2IP, 4IP, and 6IP were greater than SC steers (P < 0.05), and ADG by steers treated with 6IP was greater (P < 0.05) than steers given 2IP or 4IP. Trial 2 was a multisite grazing study performed with heifers and steers to compare ADG after treatment with one 6-pellet, coated implant delivering 21 mg EB and 150 mg TBA (6IP) to sham treated negative controls (SC) over a grazing period of at least 200 d. A completely random design was used at each site, with the goal to treat 70 cattle per site, treatment, and sex; data were pooled across sites. Heifers (n = 558, initial BW = 229 ± 16 kg) and steers (n = 555, initial BW = 235 ± 20 kg) grazed in rotational programs consistent with regional practices for an average of 202 d. When necessary, cattle were supplemented with preserved forage, but no concentrate supplements were fed. Over 202 d, ADG by heifers treated with 6IP was 11.3% greater (P = 0.0035) than SC heifers (0.64 ± 0.06 kg/d), and ADG by steers treated with 6IP was 17.2% greater (P = 0.0054) than SC steers (0.66 ± 0.08 kg/d). In neither study was there evidence that concurrent therapeutic treatments or abnormal health observations were influenced by experimental treatments. These studies demonstrated that a 6-pellet implant with a polymeric, porous coating that delivers 21 mg EB and 150 mg TBA improved ADG by grazing heifers and steers for at least 200 d compared to sham-implanted negative controls.

Effects of estradiol benzoate and trenbolone acetate, alone or in combination at dose levels present in Synovex Choice, on performance by feedlot heifers.

Trials were conducted with beef heifers at 4 sites to evaluate feedlot performance and carcass characteristics in response to implants containing 14 mg estradiol benzoate and 100 mg trenbolone acetate (EB/TBA; Synovex Choice, Zoetis LLC, New York, NY), 14 mg estradiol benzoate (EB), 100 mg trenbolone acetate (TBA), or a sham-implanted control (SC). The study design at each site was a randomized complete block with 12 blocks and 4 treatments. Blocks of cattle at each site were harvested in commercial abattoirs when masked personnel estimated at least 60% of animals would yield carcasses with USDA quality grades of Choice or Prime. Data were pooled across sites for statistical analysis. Initial BW averaged 374 kg, and days on feed ranged from 98 to 126 d (mean 112 d). Heifers implanted with EB/TBA, EB, and TBA had greater ADG and G:F (P < 0.05) than SC; ADG and G:F were greater for EB/TBA than EB or TBA (P < 0.05). Heifers treated with TBA had greater G:F than EB (P < 0.05). Feed intake was not affected by treatments. Mean HCW and LM area for EB/TBA were greater than for other treatments (P < 0.05). Mean HCW for TBA was greater than SC (P < 0.05) but not different from EB. Mean LM area for EB and TBA were greater than SC (P < 0.05) but not different from each other. There were no treatment differences (P > 0.05) for KPH, 12th-rib fat thickness, or yield grade. Dressing percent was greater for EB/TBA than SC (P < 0.05) but not different from EB or TBA. Marbling score was decreased by EB/TBA (P < 0.05) compared with other treatments, but no other differences were noted. Despite the effect of EB/TBA on marbling scores, there were no significant (P > 0.05) treatment differences on proportions of carcasses with quality grades ≥ Choice vs. < Choice. With respect to ADG and G:F, implants containing EB, TBA, or EB/TBA produced improved responses over SC. Furthermore, EB/TBA induced greater ADG and G:F responses than EB and TBA. Results confirmed that EB and TBA have additive effects, as evidenced by the observation that calves implanted with EB/TBA had significantly greater ADG and G:F than heifers implanted with either EB or TBA alone or compared with SC heifers.

Synovex Plus implants coated with a polymeric, porous film improve performance of beef steers and heifers fed in confinement for up to 200 days.

Synovex Plus (SP) is a product that delivers 28 mg of estradiol benzoate (EB) and 200 mg of trenbolone acetate (TBA). We studied the impact of a polymeric, porous coating on SP implants (CSP) to prolong release of EB and TBA, and stimulate feedlot performance of feedlot cattle for an extended period. In an explant study, 30 steers were implanted with SP in one ear and CSP in the contralateral ear. Cattle (n = 6/d) were necropsied 40, 81, 120, 160, and 200 d after treatment, and remaining EB and TBA were quantified. Linear regression of EB and TBA remaining as a function of time for each treatment were computed. Rates of EB and TBA depletion from SP were -0.1980 (r(2) = 0.9994) and -1.7073 mg/d (r(2) = 0.9644), respectively, and for CSP rates of EB and TBA depletion were -0.1049 (r(2) = 0.9123) and -0.9466 mg/d (r(2) = 0.9297), respectively. The effect of treatment on depletion rates of each analyte were significant (P < 0.05). Data also showed EB and TBA were delivered from CSP at least 200 d but were delivered from SP about 120 d. Multisite trials with beef-type steers (4 sites) and heifers (4 sites) evaluated feedlot performance and carcass characteristics in response to a CSP implant or when sham implanted (SC). A randomized complete block design with 9 blocks and 2 treatments was used per site within animal gender. Across sites, steers (n = 342, BW = 297 kg) were fed finishing rations for 190 to 202 d (mean 198 d) and heifers (n = 342, BW = 289 kg) were fed finishing rations for 191 to 201 d (mean 198 d). Cattle were harvested and carcasses evaluated. Data were pooled across sites within gender for statistical analysis. Steers and heifers treated with CSP yielded greater (P ≤ 0.003) ADG, DMI, and G:F than SC steers and heifers. Mean BW differences between CSP and SC continued to increase throughout the study, indicating CSP stimulated growth of steers and heifers for 198 d. Mean carcass weights of CSP steers (P = 0.005) and heifers (P = 0.004) were greater than those of SP steers and heifers by 26.2 and 20.6 kg, respectively. The LM area was larger (P < 0.001) in CSP steers and heifers than SC cattle. Marbling decreased with CSP treatment (P ≤ 0.031), which caused reductions (P ≤ 0.006) in proportions of carcasses grading Prime or Choice. Evidence from these studies showed that a single administration of CSP increased feedlot cattle performance for at least 198 d, compared with SC, and may reduce the need to reimplant cattle.

Pharmacokinetic and pharmacodynamic evaluation of propofol administered to cats in a novel, aqueous, nano-droplet formulation or as an oil-in-water macroemulsion.

This study evaluated pharmacokinetic and pharmacologic properties of a novel, non-lipid microemulsion, 1% w/v formulation of propofol to a conventional macroemulsion formulation of propofol (Rapinovet) in cats. The study utilized a two-period crossover design with two treatments and 10 female, intact, purpose bred domestic shorthair cats. Cats were fitted with telemetry transmitters for direct measurement of arterial blood pressure, pulse rate, electrocardiogram (ECG, lead II), and body temperature. At least 7 days separated treatments. Orotracheal intubation was the clinical endpoint utilized to evaluate adequate depth of anesthesia. Blood samples were drawn from jugular vascular access ports before propofol treatment; 3, 5, 15, 25, 35, 45, and 60 min and then 2, 3, 6, 8, 12, 18, and 24 h after administration of propofol into a cephalic vein. Whole blood samples were assayed for propofol concentrations using a gas chromatography/mass spectrometry method validated for feline blood at a limit of quantification of 5 ng/mL. Pulse rate, ECG, heart rhythm, respiratory rate, systolic, diastolic and mean arterial blood pressures, SpO2, and body temperature were monitored continuously during each anesthetic episode. Time to lateral recumbency, orotracheal intubation, and extubation, time to sternal recumbency during recovery, times to adverse events, and doses of propofol required for induction to anesthesia were documented. Cats required 6.96 +/- 0.90 mg propofol/kg from the novel microemulsion formulation of propofol and 7.07 +/- 1.55 mg propofol/kg from Rapinovet to achieve anesthesia adequate to allow orotracheal intubation (P > 0.05). Areas under the dose-normalized propofol concentration by time curves (AUC(0-LOQ)) and maximum propofol concentrations (C(max)) were equal for the novel microemulsion formulation of propofol and Rapinovet (P > 0.05). Effects of anesthesia induction doses on cardiorespiratory values were comparable between treatments, and consistent with known effects of propofol anesthesia. Results provide evidence that the novel microemulsion formulation of propofol and Rapinovet macroemulsion produced comparable pharmacodynamic, physiological, and pharmacokinetic responses in cats. The unique composition of the microemulsion formulation, and the presence of an antimicrobial preservative minimize the potential for bacterial contamination and prolong shelf life.

A multicenter evaluation of the effectiveness of Quest Gel (2% moxidectin) against parasites infecting equids.

Controlled trials with a common protocol were conducted in Idaho, Illinois and Tennessee to evaluate anthelmintic effectiveness of Quest Gel (QG; 2% moxidectin) against lumenal parasites in horses. Candidate horses were required to have naturally acquired nematode infections, as confirmed by presence of strongylid eggs in feces. At each site, 24 equids were blocked on the basis of pretreatment strongyle fecal egg counts (EPG) and randomly assigned to treatments within blocks. Within each block of two animals, one received QG on Day 0 at a dosage of 0.4 mg moxidectin/kg b.w. and one was an untreated control. Body weights measured the day before treatment served as the basis for calculating treatment doses. Horses assigned to treatment with QG received the prescribed dose administered orally with the commercially packaged Sure Dial syringe. Horses were necropsied 12-14 days after treatment, and lumenal parasites and digesta were harvested separately from each of five organs, including the stomach, small intestine, cecum, ventral colon and dorsal colon. Parasites from stomachs and small intestines were identified to genus, species and stage. Micro- (i.e., < 1.5 cm) and macroparasites (i.e., > 1.5 cm) in aliquots from the cecum, ventral colon and dorsal colon were examined in aliquots of approximately 200 parasites until at least 600 parasites had been identified to genus, species and stage or until all parasites in the 5% aliquot were examined, whichever occurred first. Data were combined across sites and analyzed by mixed model analysis of variance to assess the fixed effect of treatment and random effects of site and block within site. Because QG does not contain a cestocide, efficacy of QG against tapeworms was not significant (P > 0.05). Based on geometric means, however, efficacy of QG was greater than 90% (P < 0.05) against 38 species and developmental stages of cyathostomes, strongyles, bots, larval pinworms and ascarids encountered in at least 6 of 36 control horses in the combined data set. None of the horses treated with moxidectin exhibited evidence of adverse effects. Study results demonstrate QG, administered to horses with naturally acquired endoparasite infections at a dosage of 0.4 mg moxidectin/kg b.w., was highly effective against a broad range of equine parasitic infections.

Effects of subcutaneous injections of a long acting moxidectin formulation in grazing beef cattle on parasite fecal egg reduction and animal weight gain.

Trials were conducted in Arkansas, Idaho, Illinois and Wisconsin using a common protocol to evaluate effectiveness and safety of a long acting (LA), oil-based injectable formulation of moxidectin in beef cattle grazing spring and/or summer pastures. At each site, 150 cattle (steers and/or heifers) were blocked based on pretreatment fecal strongyle egg counts (EPG) and then randomly assigned to treatments within blocks. Presence of naturally acquired parasitic infections, confirmed by presence of parasite eggs in feces, was a prerequisite for study enrollment. Within each block of three animals, two received moxidectin LA injectable on day 0 at a dosing rate of 1.0 mg moxidectin/kg b.w. into the dorsal aspect of the proximal third of the ear, and one received a placebo control treatment. Cattle were weighed before treatment and on day 55 or 56 (55/56) after treatment. Fecal samples were also collected from 10 randomly selected blocks of animals at each site on days 14, 28 and 55/56 for EPG quantification. Average daily gain (ADG) was computed over the posttreatment period. Data pertaining to ADG and EPG were combined across sites and analyzed by mixed model analysis of variance to assess the fixed effect of treatment and random effects of site, block within site and the treatment by site interaction. Compared to placebo-treated controls, the geometric means of fecal EPG counts from cattle treated with moxidectin LA injectable were reduced 99.8% 14 days after treatment, 99.1% 28 days after treatment and 96.7% 55/56 days after treatment. Rate of weight gain by cattle treated with moxidectin LA injectable was 0.59 kg/day, or 23% (0.11 kg/day) more than placebo-treated controls (P<0.05). None of the cattle treated with moxidectin LA injectable exhibited signs of macrocyclic lactone toxicosis. Summarized across all study sites, proportions of cattle that received concurrent therapeutic treatments were similar among treatment groups. Study results demonstrate that moxidectin cattle LA injectable administered at a dosing rate of 1.0 mg moxidectin/kg b.w. to grazing beef cattle was effective and safe.

Persistent activity of moxidectin long-acting injectable formulations against natural and experimentally enhanced populations of lice infesting cattle.

A study was conducted under a common protocol in Wisconsin and Wyoming, USA, to evaluate therapeutic and persistent efficacy of two long-acting injectable formulations of moxidectin against lice populations infesting cattle. At each site, 30 beef calves were blocked into groups of three based on naturally acquired Linognathus vituli populations, then randomly assigned to treatments within blocks. Treatments, injected subcutaneously into the proximal third of the ear on Day 0, included saline, a long-acting oil-based formulation containing 10% moxidectin given at the rate of 1 mg moxidectin/kg body weight (M10/1.0), or a long-acting oil-based formulation containing 15% moxidectin given at the rate of 0.75 mg moxidectin/kg b.w. (M15/0.75). Species of sucking and chewing lice were quantified on nine predilection sites before treatment, then 28, 63, 98, 133 and 168 days after treatment. During intervals between lice counts after Day 28, study animals from the three treatment groups were commingled for 32 days with two lice-free sentinels plus four to six seeder calves with infestations of both sucking and chewing lice. Following each 32-day commingling interval, seeder and sentinel animals were removed, and principal animals were sorted into pens by treatment. Lice were quantified on sentinel animals on the day of removal, and lice were quantified on principal study animals 3 days after removal of sentinel and seeders. Moxidectin was generally not efficacious against Bovicola bovis in the injectable formulations tested, whereas Haematopinus eurysternus infestations were inadequate to judge product effectiveness. Based on geometric means, both M15/0.75 and M10/1.0 provided statistically significant therapeutic efficacy against existing infestations of L. vituli and Solenopotes capillatus (100% efficacy on Day 28), and provided persistent protection against reinfestation with L. vituli and S. capillatus (efficacy >97%) for at least 133 days following treatment.

Dose confirmation studies of moxidectin 1% non-aqueous injectable and moxidectin 0.5% pour-on formulations against experimentally induced infections of larval and adult stage Oesophagostomum radiatum and Trichuris discolor in cattle.

Separate controlled trials were conducted to evaluate the efficacy of two formulations of moxidectin (1% non-aqueous injectable solution and 0.5% pour-on (Cydectin) against larval or adult stages of Oesophagostomum radiatum and Trichuris discolor infecting cattle. Fifty-three strongylate-free dairy breed steer calves were obtained from commercial sources. After a brief acclimation period, calves were randomly divided into two pools to evaluate the efficacy of the moxidectin formulations against targeted larval (n = 27 calves) or adult (n = 26 calves) parasites. Calves in the larvacidal trial were inoculated on Day -16 relative to treatment with approximately 1000 embryonated Trichuris spp. eggs and approximately 640 infective Oesophagostomum spp. larvae. Calves were allocated by lottery to one of three treatment groups (n = 8 per group), which included: Group 1--moxidectin 0.5% pour-on (0.5 mg/kg body weight (BW)) applied topically; Group 2--moxidectin 1% non-aqueous injectable (0.2 mg/kg BW) administered subcutaneously; Group 3--untreated controls. Treatments were administered on Day 0 and calves were housed by group with no contact among animals of different treatments. Three sentinel calves were necropsied on Day 0 of the larvacidal trial to assess viability of larval inocula. On Days 14, 15 and 16 after treatment, calves were euthanatized (two or three from each group per day) and samples of gut contents were collected for determination of total worm counts. On Day -63 relative to treatment, calves in the adulticidal efficacy trial were inoculated with approximately 1000 embryonated Trichuris eggs and then on Day -35 with approximately 2500 infective Oesophagostomum spp. larvae. Fecal samples were collected on Day -7 and the 24 calves with the highest egg counts were assigned by lottery to the following three treatment groups (n = 8 per group): Group 4--moxidectin 0.5% pour-on; Group 5--moxidectin 1% injectable; Group 6--untreated controls. Details of experimental treatments, calf housing and necropsy scheduling were similar to the larvacidal trial. In both the larvacidal and adulticidal trials, inocula contained a variety of parasites in addition to the targeted species. Based on geometric means, both moxidectin 0.5% pour-on and moxidectin 1% non-aqueous injectable significantly reduced (P < 0.05) numbers of Oesophagostomum spp. and Trichuris spp. with anthelmintic efficacies of >99% when used against adult or larval stages of infection. In addition, both formulations of moxidectin demonstrated >95% efficacy (P < 0.05) against larval stages of Strongyloides papillosus. The pour-on formulation had >97% adulticidal and larvacidal efficacy against Cooperia spp. females, while the injectable product was effective against female Cooperia spp. larvae and Cooperia oncophora adult males.

Effects of alpha2-adrenoceptor antagonists on metabolic processes of swine: I. Effects on nonesterified fatty acid and plasma urea nitrogen concentrations in jugularly catheterized pigs.

The presence of alpha2-adrenoceptors in membranes from omental and s.c. adipose tissue from gilts and barrows was shown in saturation binding assays with [3H]yohimbine. Four trials tested effects of alpha2-adrenoceptor antagonists (A2AA) on plasma concentrations of NEFA and urea nitrogen (PUN). In Trial 1, barrows were given i.v. injections of saline, 200 microg/kg BW of one of three A2AA (efaroxan, idazoxan, or RX821002), or 25 microg/kg BW of isoproterenol. Concentrations of NEFA were measured in plasma harvested every 15 min from 1 h before to 2 h after treatment. Compared with results for saline-treated pigs, areas under the curve (AUC) for NEFA were increased (P < .05) by efaroxan, RX821002, and isoproterenol. In Trial 2, barrows received i.v. doses of saline, efaroxan (200 or 400 microg/kg BW), or RX821002 (200 or 400 microg/kg BW). Levels of NEFA were quantified in plasma obtained at 15-min intervals through 2 h after treatment. Among pigs treated with RX821002 at 400 microg/kg BW, mean NEFA AUC was more than three times greater (P < .05) than that for saline-treated animals. Trial 3 tested whether NEFA responses to A2AA were due to direct effects on alpha2-receptors or involved beta-adrenoceptor mediation. Pigs were first treated i.v. with saline or propranolol (1 mg/kg BW). One hour later, pigs were treated i.v. with RX821002 (400 microg/kg BW) or the beta-adrenoceptor agonist cimaterol (25 microg/kg BW). Compared to values for pigs treated with saline at both injections, NEFA AUC among pigs treated with saline at the first injection and RX821002 at the second doubled (P > .05). Plasma NEFA AUC among pigs treated with saline then cimaterol rose nearly fourfold (P < .05) compared with saline-treated controls. Mean NEFA AUC among propranolol-treated pigs was similar to values for saline-treated pigs, suggesting beta-adrenoceptor involvement in the effect of A2AA on NEFA. In Trial 4, pigs were treated s.c. 10 times at 8-h intervals with saline, RX821002 (400 microg/[kg BW x injection]), cimaterol (20 microg/[kg BW x injection]) or recombinant porcine somatotropin (rpST; 1 mg/[pig-injection]). After the 10th treatment, only cimaterol increased NEFA AUC compared to saline-treated controls (P < .05). Mean PUN AUC was reduced by RX821002 and rpST compared to controls; PUN among rpST-treated pigs was lower than that among RX821002-treated pigs (P < .05). In summary, A2AA increase lipolysis in swine by potentiating lipolytic effects of endogenous catecholamines on beta-adrenoceptors. Reduced PUN suggests improved nitrogen efficiency may result from treatment with A2AA.

Effects of alpha2-adrenoceptor antagonists on metabolic processes of swine: II. Nitrogen balance responses.

We studied the effects of alpha2-adrenoceptor antagonists (A2AA) on nitrogen (N) partitioning. The diets fed contained 19.8% CP and 1.15% lysine. Pigs were fed the diet as a percentage of BW equaling approximately 90% of voluntary intake. In Trial 1, pigs (n = 11/treatment) were fed a basal diet and injected s.c. at 8-h intervals for 11 d with saline, RX821002 (25 mg/injection), or cimaterol (.6 mg/injection). Compared to saline-treated pigs, urinary N, as a percentage of N eaten, decreased among pigs injected with RX821002 (15%, P < .05) or cimaterol (17%, P < .05). In Trial 2, pigs got saline (n = 6) or 25 mg RX821002 (n = 6) as s.c. injections three times daily, or they were fed a diet containing 150 ppm RX821002 and injected thrice daily with saline (n = 6) for 11 d. The RX821002 lowered apparent DM and N digestibility (P < .05). Compared to controls, RX821002 lowered urinary N, as a percentage of N eaten, 15 and 18% when given by injections or per os, respectively, but effects were not significant. Trial 3 evaluated the effects of RX821002 fed at levels of 0 (n = 6), 37.5 (n = 5), 75 (n = 6), or 150 ppm (n = 6). Contrasts showed linear dose-dependent decreases in gain and apparent N digestibility (P < .05). Compared to untreated controls, urinary N, expressed as a percentage of N consumed, decreased 2, 12, and 10% among pigs fed diets with 37.5, 75, or 150 ppm RX821002, respectively, but effects were not significant. Trial 4 compared N balance in pigs (n = 6/treatment) fed basal diet or diet with 100 ppm RX821002 to that of pigs fed diets with 25 or 100 ppm yohimbine. Treatments reduced apparent N and DM digestibility (P < .05). Urinary N, as a percentage of N consumed, decreased 16 (P > .05), 18 (P < .05), and 24% (P < .05) for 100 ppm RX821002, 25 ppm yohimbine, or 100 ppm yohimbine, respectively. Data from Trials 2, 3, and 4 from control pigs (n = 18) or pigs fed A2AA (all A2AA sources and doses; n = 41) were pooled and analyzed. Feeding A2AA decreased apparent N and DM digestibility (P < .01). The fact that fecal moisture content was higher in pigs fed A2AA suggests rate of digesta passage increased and offers an explanation for reduced N and DM digestibility in treated pigs. Despite adverse effects of A2AA, efficiency of postabsorptive N metabolism increased. As a percentage of N consumed and compared to control pigs, urinary N decreased 15% (P < .01) and retained N increased 12% (P < .05) in animals fed A2AA. Data from these studies show net efficiency of N metabolism is improved in swine given A2AA.

Dose titration of sustained-release recombinant bovine somatotropin in lactating dairy cows.

Lactating dairy cows (n = 264) were used in seven dose titration experiments at four geographic locations in the United States. A sustained-release formulation of recombinant bST was evaluated for a 30-wk treatment period that began 14 wk postpartum. The first series of four experiments evaluated doses of 0, 140, 350, or 700 mg of bST/14 d (series A); the second series evaluated doses of 0, 56, 140, or 350 mg of bST/14 d (series B). Milk yield, DMI, milk composition, body condition, health, and reproductive parameters were measured. Multiparous cows in series A that were administered 700 mg of bST/14 d yielded 3.0 kg/d more milk and 3.5% FCM than control cows. When all seven experiments were combined, multiparous cows that were administered 350 mg of bST/14 d yielded 2.7 and 2.6 kg/d more milk and 3.5% FCM than control cows. Dry matter intake was not significantly affected by bST administration. In series A, an increase in milk yield with no increase in DMI resulted in lower adequacy of dietary NEL and CP to meet maintenance and yield requirements among multiparous cows administered 700 mg of bST/14 d. Primiparous cows that were administered bST in series A and both parity groups in the combined seven experiments were not different from control cows in the adequacy of dietary NEL or CP to meet maintenance and yield requirements. No adverse effects of bST on health parameters were significant, and doses of 350 mg of bST/14 d or less caused no changes in reproductive parameters. Conception rate was decreased by administration of 700 mg of bST/14 d. These data suggest that 350 mg of bST/14 d increased yields of milk and FCM with no adverse effects on DMI, health, or reproduction in dairy cows.

Influence of bovine somatotropin and nutrition on production and composition of milk from dairy cows.

Forty-eight multiparous Holstein cows were used in an experiment with a 2 x 2 factorial arrangement of treatments to study interactions of bST and nutrient density during wk 5 through 20 postpartum. Main effects were bST (0 or 10.3 mg/d) and diet (control or high protein and energy). The control diet was formulated to contain 16.3% CP and 1.65 Mcal of NEL/kg of DM; the high protein and energy diet was formulated to contain 18% CP and 1.74 Mcal of NEL/kg of DM with additional energy as fat from extruded soybeans and calcium salts of fatty acids. Diet ratios were 50:25:25 for concentrate:alfalfa hay:corn silage (DM basis). Bovine somatotropin increased milk production (40.9 vs. 37.9 kg/d) and production of 4% FCM (35.7 vs. 32.3 kg/d). The high protein and energy diet increased milk production (40.3 vs. 38.5 kg/d); 4% FCM production was higher for high protein and energy plus bST (36.0 kg) than without bST (33.6 kg). Percentage of milk fat was not affected by treatment. Percentage of milk protein was reduced with the high protein and energy diet, presumably because of the added fat, but this reduction was less with high protein and energy plus bST. Dry matter intake was not significantly elevated by bST (23.1 vs. 22.8 kg/d) but was lower for high protein and energy (22.0 vs. 23.8 kg/d). Increased dietary protein and energy with bST augmented the total milk production response.

High-moisture corn utilization in finishing cattle.

Two finishing trials, one laboratory trial and one metabolism trial were conducted with the following objectives: 1) to determine the associative effects of feeding high-moisture corn (HMC) with either dry-rolled grain sorghum (DRGS) or dry-rolled corn (DRC) and 2) to evaluate HMC when harvested at different moisture levels, stored in different structures, or fed as whole or rolled HMC. In Trial 1, yearling steers (BW, 328 kg) were fed diets containing mixtures of HMC and DRGS. As level (0, 33, 100%, as percentage of grain DM) of DRGS increased, ADG (P less than .03) and gain/feed (P less than .001) decreased linearly; gain/feed tended to be affected quadratically (P = .14). In Trial 2, yearling steers (BW, 382 kg) fed HMC, stored whole in an upright, oxygen-limiting silo and rolled coarsely before feeding, gained faster (1.46 vs 1.36 kg/d) and more efficiently (.142 vs. .131 gain/feed) than steers fed whole HMC (P less than .01). In Trial 3, as length of storage of bunker HMC increased, in vitro rate of starch digestion and soluble N content increased (20.4 and 36.8%, respectively) and grain pH decreased (10.9%). In Trial 4, steers fed HMC or a mixture of 75% HMC with 25% DRGS had similar ruminal pH throughout a grain adaptation period, but total ruminal VFA were greater (P less than .005) for steers fed HMC alone. These data are interpreted to suggest that feeding a mixture of HMC, ground and stored in a bunker or silo bag, with DRGS will result in a 3.2% associative effect. However, no associative effects were measured when a mixture of HMC, stored whole and fed whole or rolled, and DRC were fed.

Dose response to recombinant bovine somatotropin from weeks 15 to 44 postpartum in lactating dairy cows.

Forty Holstein cows were used in an experiment to determine the response of cows to daily subcutaneous injections of 0, 10.3, 20.6, and 30.9 mg of recombinant bST. Injections began between 98 and 104 d postpartum and continued for 29 wk, up to 70 d prepartum, or a maximum of 400 d postpartum. Increasing recombinant bST increased milk yield and 3.5% FCM yield in a linear fashion and by 5.2 and 5.7 kg/d, respectively. Milk composition was not changed, and DM intake as a percentage of BW increased from 3.39 to 3.80% with increasing (30.9 mg/d) bST. Feed efficiency (3.5% FCM/DM intake) was increased from 1.35 to 1.64 with increasing dose, suggesting improved efficiency of use of DM intake, primarily by dilution of maintenance. Increasing bST reduced BW gain linearly from .46 kg/d for the control to .22 kg/d for the 30.9 mg/d bST. Calf birth weight, weight of cows at calving, and incidence of metabolic diseases during subsequent calving were not affected by bST. Somatotropin treatment resulted in somewhat smaller increased in milk yield than that reported in previous studies. Long-term health effects and effects on reproduction could not be determined from the relatively few cows used in this study.

Lactational evaluation of recombinant bovine somatotropin with corn and barley diets.

Forty-eight Holstein cows were randomly assigned to receive diets containing corn or barley as the primary energy concentrate from wk 4 through 44 postpartum. During wk 14, cows from each grain source group were randomly assigned to receive 0 (control), 10.3, 20.6, and 30.9 mg/cow per d of recombinant bST injected wk 15 through 44 postpartum. Grain source exerted no significant effect on production parameters and efficacy of bST, although milk production tended to be higher with corn diets. Milk production (24.2, 29.2, 31.7, and 29.5 kg/d) and 4% FCM (21.9, 26.2, 28.1, and 28.0 kg/d) were higher for cows injected with bST, and DM intakes (20.9, 22.8, 22.0, and 23.3 kg/d) increased slightly. Percentages of milk fat (3.47, 3.28, 3.39, and 3.52) and protein (3.48, 3.44, 3.44, and 3.38) varied. Lactose, SCC, and body weights were similar for bST and dietary treatments. Diet or bST had no detectable affect on health or reproduction. Injection of bST wk 15 through 44 increased milk production 21 to 31% relative to control animals. Limiting bST use to the latter two-thirds of lactation resulted in an 8 to 17% increase in total yield with only a 0 to 5% increase in lactational DM intake.

Response to recombinant bovine somatotropin in dairy cows with different genetic merit for milk production.

Thirty-nine multiparous cows obtained from two genetic lines were utilized to determine the effect of genetic merit on lactation response to long-term administration of recombinant bST. Cow index ranged from -70 to 456 (mean = 183) and -494 to -88 (mean = -288) kg milk for high and low genetic groups, respectively. Cows were blocked by calving date and randomly assigned to treatment within genetic group. Treatments were 0, 10.3, 20.6, and 30.9 mg somatotropin injected daily from wk 14 through 44 postpartum. Cows were fed one of two total mixed rations. Diet 1 (NE1 = 1.65 Mcal/kg, CP = 18%, and ADF = 22%) was fed from start of lactation to at least 4 wk after initiation of treatment. Cows were switched to diet 2 (NE1 = 1.56 Mcal/kg, CP = 16%, and ADF = 27%) when milk output fell below 25 kg/d. Forty-four week lactation yields were 9800 and 9447 kg milk; 364 and 354 kg fat; and 322 and 309 kg protein for high and low genetic groups, respectively. Milk, milk fat, or protein yield due to somatotropin did not differ between genetic groups. Increasing dosage of bST increased milk, 4% FCM, fat, and protein yields in a linear fashion. Percentages of fat and protein of milk were similar for all treatment groups. Body weight changes were not significantly different among treatments, but condition score changes decreased linearly with increasing dose of bST. Long-term treatment with recombinant bST had no apparent effect on incidence of health problems or reproduction.

Induced non-enzymatic browning of soybean meal. I. Effects of factors controlling non-enzymatic browning on in vitro ammonia release.

Non-enzymatic browning was tested as a means of suppressing degradation of soybean meal (SBM) by ruminal microbes in five trials with in vitro ammonia release as the response criterion. Treatments imposed on SBM included reducing sugar source (xylose, glucose, fructose and lactose), reducing sugar level (1, 3 and 5 mol/mol SBM-lysine), pH (6.5, 8.5 and 10.0), dry matter (DM) content (65, 70, 75, 80, 85 and 90%) and varying lengths of heating time (0 to 90 min) at 150 C. Samples heated under conditions that promoted non-enzymatic browning gave greater (P less than .01) ammonia release suppression that when SBM was heated without these treatments. Xylose was the most reactive sugar, but extended heating of SBM containing glucose, fructose or lactose resulted in ammonia release similar to xylose. Increasing sugar level from 1 to 5 mol/mol SBM-lysine caused linear decreases (P less than .01) in ammonia release for xylose, glucose and fructose, but not lactose. Ammonia release was higher (P less than .01) at pH 6.5 than pH 8.5 and 10.0, and higher (P less than .01) at pH 9.5 than pH 10.0. Rate of non-enzymatic browning decreased when samples containing greater than 80% DM were heated. These results are interpreted to show that controlled non-enzymatic browning may be effective for reducing ruminal degradation of SBM.

Induced non-enzymatic browning of soybean meal. II. Ruminal escape and net portal absorption of soybean protein treated with xylose.

Non-enzymatic browning was tested as a means of increasing ruminal escape of soybean meal N. Soybean meal was treated with xylose (3 mol/mol SBM-lysine), sodium hydroxide (pH 8.5) and enough water to achieve an 83% dry matter mixture and then heated at 150 C for 30 min (XTS-30). Trial 1 evaluated ruminal escape of N from XTS-30 compared with commercial soybean meal (CS) or urea (U) in a replicated 3 X 3 Latin square design using six duodenally cannulated Angus X Hereford steers (24.7 kg). Duodenal flow of dietary N was higher (P less than for steers fed XTS-30 (47.9 g/d) than for steers fed CS (39.5 g/d). The ruminal escape estimate for XTS-30 (33.7%) was higher (P less than .10) than CS (13.1%), whereas total tract apparent N digestibility was not different among treatments. In trial 2, net portal absorption of alpha-amino N was measured in Finnsheep X Suffolk ram lambs (24.7 kg) fed U, CS or XTS-30 in a 3 X 3 Latin square design. Portal blood flow was measured by primed, continuous infusion of para-aminohippuric acid. Portal blood flow was lower (P less than .05) for U.fed lambs than for lambs fed CS or XTS-30, and tended to be lower for lambs fed CS than those fed XTS-30. Net portal absorption of alpha-amino N tended to be lowest for lambs fed U (281 mmol/d) and highest for lambs fed XTS-30 (578 mmol/d). The results are interpreted to show that non-enzymatic browning increased flow of soybean meal N to the intestine.

Induced non-enzymatic browning of soybean meal. III. Digestibility and efficiency of protein utilization by ruminants of soybean meal treated with xylose or glucose.

Trials were conducted to evaluate effects of non-enzymatic browning of soybean meal (SBM) on efficiency of protein utilization and N digestibility. In trial 1, 48 Suffolk-Finnsheep lambs (22 kg) were fed 80 d to evaluate efficiency of protein utilization for growth when supplemental protein was fed as urea (U), commercial SBM (CS), or commercial SBM (pH 8.5, 83% dry matter) containing xylose (3 mol/mol SBM-lysine) and heated 30 min (XTS-30) or 55 min (XTS-55). Diets containing graded levels of N from CS, XTS-30 and XTS-55 were fed. Response criterion was efficiency of protein utilization, plotted as gains of lambs fed test proteins minus gain of lambs fed U vs supplemental test protein fed. Efficiencies of protein utilization were .62, 1.27 and .91 for CS, XTS-30 and XTS-55, respectively. Protein from XTS-30 was used more efficiently (P less than .05) than that from CS. In trial 2, apparent digestibility of N from CS (97%) was higher (P less than .01) than XTS-30 (77%) and XTS-55 (82%) by Suffolk-Finnsheep lambs (27 kg). In trial 3, 60 mixed-breed steers (218 kg) were fed individually for 105 d to evaluate glucose as a reducing sugar. Glucose-treated SBM (GTS) was prepared by mixing glucose (3 mol/mol SBM lysine) with SBM, adjusting pH and dry matter content to 8.5 and 80%, respectively, and heating at 150 C for 60 min. Supplemental N sources were U, CS, GTS and a 50:50 mixture (protein basis) of corn gluten meal and blood meal (CGM/BM).(ABSTRACT TRUNCATED AT 250 WORDS)