The Impact of Bacillus subtilis PB6 and Chromium Propionate on the Performance, Egg Quality and Nutrient Metabolizability of Layer Breeders

The objective of this study was to evaluate the effects of Bacillus subtillis PB6, chromium propionate or a combination of the two on the performance, egg and eggshell quality, nutrient metabolizability and serum biochemistry of layer breeders. White Plymouth Rock and Red Rhodes Island breeder hens at 55 weeks of age were allocated in individual cages using a completely randomized block design with 16 replicates. Hens were fed control, control + probiotic (500 g/ton of Bacillus subtilis PB6), control + CrProp (50 g/ton of chromium propionate) and control + probiotic + CrProp diets from 55 to 70 weeks of age. Productive parameters and eggshell quality as well as cortisol and blood biochemistry were grouped each 28 d as well as for the overall period. The metabolizability of nutrients and energy was determined at 70 weeks of age. In the overall period, hens fed the control + probiotic or control + probiotic + CrProp diets had significantly higher egg production, egg mass, shell percentage, thickness and shell strength. The metabolizability of dry matter, nitrogen and energy increased in hens that were fed the control + probiotic + CrProp diet. In conclusion, diets supplemented with Bacillus subtillis PB6 and chromium propionate resulted in improved productive performance, eggshell quality and nutrient metabolizability of layer breeders, without modifying serum cortisol, albumin and triglycerides.

298 The Effects of Chromium Propionate Supplementation to Calf-fed Steers in a Commercial Feedyard on Growth Performance, Carcass Characteristics and Health

Crossbred steers [British x Continental x Bos Indicus; n = 1844; initial body weight (BW) = 248 ± 28 kg] were used to evaluate the effects of chromium propionate supplementation to calf-fed steers in a commercial feedyard on growth performance, carcass characteristics and health. Steers were blocked by initial BW; pens were assigned randomly to one of two dietary treatments within block. Treatments, replicated in 15 pens/treatment with 57 to 62 head per pen, included: 1) control, 0 mg supplemental Cr/kg dietary dry matter (DM) (CTL); 2) 0.50 mg supplemental Cr/kg dietary DM (chromium propionate; KemTRACE® Chromium 0.04%, Kemin Industries, Des Moines, IA) (CR). Due to inadvertent oversight, during the final 30 days on feed, CR cattle did not receive trace minerals, vitamins, an ionophore, antibiotic, or ractopamine-hydrochloride. Final BW, average daily gain (ADG) and DM intake did not differ among treatments (P ≥ 0.25). Gain efficiency was greater (P = 0.03) for CTL than CR (0.16 vs. 0.15). Hot carcass weight and dressing percentage were similar among treatments (P ≥ 0.19). Yield grade was higher for CR than CTL (2.44 vs. 2.27; P < 0.01); 12th-ribfat tended to be greater for CR than CTL (P = 0.09), and longissimus area was greater for CTL vs. CR (P < 0.01). Marbling score tended (P = 0.10) to be greater for CR than CTL. Steers fed CR tended (P = 0.07) to have a greater distribution of prime carcasses than CTL (1.9% vs. 0.07%), and percentage choice carcasses was higher for CR than CTL (67.34% vs. 61. 71%, P = 0.01). Respiratory morbidity (12.20%), and retreatment rate did not differ among treatments (P ≥ 0.20). In the absence of a beta-agonist, CR steers had higher quality carcasses, and similar ADG and HCW to CTL.

297 The Effects of Chromium Propionate Supplementation to Yearling Steers in a Commercial Feedyard on Growth Performance, Carcass Characteristics and Health

British crossbred steers [n = 3074; initial body weight (BW) = 358 ± 37 kg] were used to evaluate the effects of chromium propionate supplementation to yearling steers in a commercial feedyard on growth performance, carcass characteristics and health. Steers were blocked by initial BW; pens were assigned randomly to one of two dietary treatments within block. Treatments, replicated in 15 pens/treatment with 75 to 135 head per pen, included: 1) control, 0 mg supplemental Cr/kg dietary dry matter (DM) (CTL); 2) 0.50 mg supplemental Cr/kg diet DM (chromium propionate; KemTRACE® Chromium 0.04%, Kemin Industries, Des Moines, IA) (CR). Final BW (638 vs. 641 kg.), average daily gain, (1.81 vs. 1.82 kg), DM intake (11.02 vs. 11.02 kg) and gain efficiency (0.164 vs 0.165) did not differ between CTL and CR, respectively (P ≥ 0.75). No differences among treatments for hot carcass weight (407 vs. 408 kg., CTL and CR, respectively), dressing percentage, longissimus muscle area, or yield grade were observed (P ≥ 0.15). Twelfth-rib fat thickness tended (P = 0.10) to be greater for CR vs. CTL (1.55 vs 1.29 cm, respectively). A trend (P = 0.10) for marbling score to be higher for CR vs. CTL was detected (452 vs. 440, respectively). Distribution of quality grade was similar between CR and CTL; 1.52% of carcasses graded prime (P =0.68), and 87.2% of carcasses graded choice (P = 0.68). Respiratory morbidity was low (1.93%) and not different among treatments (P = 0.20); likewise, there was no difference in respiratory treatment rates between treatments (P ≥ 0.18). Supplementing Cr to high-performing yearling steers did not alter growth performance, carcass characteristics or health outcomes.

355 Mineral Metabolism

This presentation will highlight historic discoveries in mineral metabolism in ruminants. At least 15 minerals can be classified as essential based on their involvement in one or more metabolic functions in mammals. Deficiencies of all essential minerals have occurred naturally or have been induced experimentally in ruminants. Cobalt was shown to be essential for ruminants in 1935 based on its ability to correct naturally occurring deficiency signs in Australia. This discovery occurred 13 years before cobalt was shown to a component of vitamin B12. Low serum magnesium concentrations also were associated with grass tetany in cattle before magnesium was found to be essential for the rat in 1931. The value of supplemental salt for cattle was demonstrated in the 1800’s and a salt deficiency was experimentally induced in dairy cows in 1905. Over 50 years later sodium was identified as the mineral primarily responsible for salt deficiency. Naturally occurring deficiencies of phosphorus and copper were observed in grazing ruminants shortly after they were reported to be essential for rats. Copper toxicosis also became recognized as a practical problem, especially in some breeds of sheep. Selenium was shown to prevent white muscle disease in 1958. Because of its known toxicity and lack of a specific metabolic function, it was not until 1979 that Food and Drug Administration approved the addition of 0.1 mg Se/kg DM (later increased to 0.3 mg/kg) from inorganic sources to ruminant diets. This approval occurred after the identification of glutathione peroxidase as a selenium metalloenzyme in 1972. In 2009, the Food and Drug Administration approved the use of chromium propionate as a source of supplemental chromium for cattle at levels up to 0.5 mg Cr/kg DM. The approval of chromium propionate was based on its safety and ability to enhance insulin sensitivity in cattle.

Effect of Supplemental Chromium, Vitamin E and Selenium on Biochemical and Physiological Parameters of Holstein Friesian Calves under Heat Stress

Background: Heat stress has been a major concern in tropical, sub-tropical and arid areas affecting the performance of farm animals. Along with vitamin E and Selenium, chromium is gaining importance in combating heat stress. Methods: Twenty-four calves of 7- 8 months old with an average body weight of 172.79±4.39 kg were distributed randomly into four dietary treatment groups (T0, T1, T2 and T3). The calves of control group (T0) were fed on basal diet i.e. total mixed ration (TMR). The basal diet of T1, T2 and T3 on per kg DM basis were supplemented vitamin E (500 IU) + selenium (0.3 mg), chromium propionate (0.5 mg) and chromium propionate (0.5 mg) + vitamin E (500 IU) + selenium (0.3 mg), respectively. Ambient air temperature and humidity were measured for calculation of THI. Blood samples were collected fortnightly and the rectal temperature (RT), respiration rate (RR) and pulse rate (PR) of all the experimental animals were recorded twice daily to study the biochemical and physiological parameters. Result: Supplementation of chromium along with vitamin E and selenium decreased significantly (P less than 0.05) the cortisol levels and increased the albumin concentration. Chromium supplemented groups (T2 and T3) showed greater (P less than 0.05) increase in mean total protein concentration. A significant reduction in RT was observed in all the supplemented groups compared to control. Whereas, the PR and RR differed significantly in T3 group compared to control.