This study evaluated cow age and supplement intake level during gestation on the quality of colostrum at calving, cow serum immunoglobulin G (IgG) levels at parturition, and serum IgG levels of the calf 3-days post-partum using two refractometer methods. Forty-five multiparous Angus cows were selected from a contemporary group of 300 cows that were winter grazing northern mixed grass prairie rangelands with free choice protein supplement. Specifically, 15 first service bred cows were selected for each of the following winter grazing supplement intake treatment groups: 1) low supplement intake (> -0.75 SD); 2) average supplement intake (± 0.50 SD); 3) high supplement intake (> +0.75 SD). Supplement intakes were measured using a SmartFeed Pro self-feeder system with 8 feeding units. Measurements were obtained from day 164 to 215 of gestation. Cows were further divided by age comparing young (4, 5, and 6 yr) to old (7, 8 and 9 yr). The results of this study suggest that cow age did not interact with supplement intake for colostrum or blood serum measurements (P ≥ 0.29). In addition, cow age and supplement intake did not influence colostrum Brix %, calf serum total protein, or cow serum total protein taken at birth (P ≥ 0.14). The optical refractometer was found to be a good alternative to the more expensive digital refractometer (P < 0.01; R = .96). In summary, cow age and supplement intake levels of mature cows during the mid to late stages of gestation did not influence colostrum quality at birth.
Limit creep-feeding a 36% protein supplement (avg. salt concentration = 7.9%) was compared with unlimited consumption of the same supplement without salt (full creep-feeding) and with no supplementation. Average daily gain of steer calves was increased (P≤.06) by.19 (limit creep-feeding) and .38 (full creep-feeding) lb per day compared with non-supplemented calves. Average daily gain of heifer calves was not increased by creep feeding. Efficiency with which creep was converted to extra gain was poor for both limit and full creep-feeding groups. Little difference was observed in postweaning average daily gains; however, the calves given ad libitum access to creep feed tended (P=.12) to have greater daily gains (1.9 lbs) than non creep-feeding calves (1.6 lbs). Limit creep-fed calves had average daily gains of 1.7 lbs. Feed conversion during the post-weaning period was slightly improved (P=.09) in calves that had been given ad libitum access to creep feed.
Abstract The objectives of this research were to determine how daily and hourly distance traveled, grazing time, and resting time of beef cows are influenced relative to the timing of supplementation. Over two winters, a herd of commercial Angus cows grazed in a 645-ha Montana foothill rangeland pasture for 56 days between December and February each year. At 1300 every Monday, Wednesday and Friday, all cows were gathered and taken to a central location in the pasture where 3.18 kg∙hd-1 of alfalfa pellets (17% CP) were immediately delivered. Each year, 18 cows were randomly assigned a global positioning system (GPS) collar. Using the GPS collar data, distance traveled, grazing time, and resting time were estimated for each hour and day for each cow. Activity was grouped into the 24-h period pre-supplementation and 24-h period post-supplementation. Cows traveled 1.7 km further and grazed for 0.7 h less per day post-supplementation (P < 0.01). Daily resting time was similar pre- and post-supplementation (P = 0.07). Post-supplementation, cows traveled further in the afternoon and morning and reduced grazing in the afternoon and at night (P < 0.05). Cows rested less in the morning pre-supplementation and in the afternoon post-supplementation (P < 0.03). Results indicate that three times weekly supplementation alters cow activity, though differences are mostly associated with the time surrounding when supplement is delivered.
Abstract Designing research for applied beef cattle production systems has always presented challenges for Land Grant University and USDA Scientist. Specifically, creating study designs that have enough replication for statistical inference has often prompted scientists to use designs that do not closely replicate actual production systems. Past research has often used multiple replications (pens/paddocks/pastures) that utilize replication (group averages; 4 – 8 animals) means as the experimental unit. While effective in measuring average treatment responses, these types of study designs do little to describe the actual individual animal behavior and performance in a more practical production environments. Approaches to increasing statistical observations in actual production environments will be discussed in this presentation. Embracing new technologies such as GPS, activity monitors, EID tags, and feed intake monitors (C-Lock Inc, GrowSafe) combined with multiple regression modeling tools can aid in designing and publishing beef cattle production research in actual beef production environments. Research at Montana State University has utilized SmartFeed Pro and SuperSmart Feeders for strategic supplementation research on extensive rangelands and dry-land pastures for the past seven years. Results of these studies have evaluated self-fed (salt-limited; loose, pelleted, and baked molasses blocks) as well as hand-fed supplements where daily intakes are limited by the locking gate on the feeder. This presentation will summarize these studies with a focus on research designs that were successful and/or unsuccessful in respect to characterizing beef cattle performance in production settings. Our goal will be to assist the audience in the application of feed intake technology in designing future applied beef cattle research.
Two experiments were conducted to evaluate the influence of supplemental protein concentration on the intake and utilization of dormant range forage by beef cattle. In Exp. 1,97 pregnant Hereford x Angus cows (avg wt = 454 kg) were assigned randomly to three isocaloric treatment supplements: 1) low protein (LP), 13% CP; 2) moderate protein (MP), 25% CP; and 3) high protein (HP), 39% CP. In Exp. 2, 15 ruminally and 12 esophageally cannulated steers (avg wt = 319 and 355 kg, respectively) were assigned randomly to LP, MP and HP treatments and were used in a 22-d winter grazing trial to evaluate forage intake and utilization characteristics. In Exp. 1, cow body condition (BC) and BW changes responded in linear (P less than .01) and quadratic (P less than .01) fashions to increasing protein concentration, with MP and HP displaying the least BC and BW loss from trial initiation (d 1) through d 84. From d 84 to calving (avg calving date = d 120), only the HP supplement continued to be effective in minimizing BC loss (P less than .01). Calf birth weight tended (P = .17) to increase in a linear fashion to increasing supplemental protein concentration, but calf ADG and cow reproductive efficiency were unaffected (P greater than .10). In Exp. 2, forage OM intake responded in a quadratic fashion (P less than .10), with the MP treatment having the highest NDF digestibility and ruminal OM fill. In conclusion, beef cow BC and BW losses during the winter grazing period were minimized with increasing supplemental CP concentration. Intake and utilization of dormant forage by steers were improved with moderate (26%) levels of CP in the supplement.
Bermudagrass [Cynodon dactylon (L.) Pers.] is productive in summer but is dormant for much of the year. The grazing season for bermudagrass pastures can be lengthened by fall interseeding of rye (Secale cereale L.). In trial 1, performance of Stocker cattle (222 kg average BW) grazing monocultured rye (MR) followed by bermudagrass (MB) in separate pastures was compared with that of cattle grazing interseeded rye-bermudagrass pastures (IRB). Spring forage production and 1989 carrying capacity were greater (P<.01)from MR than from spring IRB but gain per animal and per hectare did not differ (P>.10)between systems. Summer bermudagrass gain and grazing days from the two systems varied by year. Overall gain per hectare of land grazed and animal grazing days per hectare were greater (P<.05) both years for the IRB system than for the combined use of MR and MB. Land Equivalent Ratio for overall gain from IRB was >2.0, indicating a greater efficiency for interseeding. In trial 2, ruminally fistulated heifers (395 kg average BW) were used to estimate forage intake and nutritional components from the two types of rye pastures. Dietary forage from MR was higher (P≤.01) in neutraldetergent fiber, ADF, and in vitro organic matter digestion (IVOMD, 48 h) and lower (P<.01)in acid-detergent lignin (ADL) and indigestible ADF (IADF) than forage from IRB. Crude protein and rates of IVOMD did not differ (P>.10) between MR and IRB dietary forage. Heifers grazing MR had higher (P<.01)OM intake, lower OM (P=.06) and IADF (P<.01) fill, and shorter (P<.05) rumen retention time than heifers grazing IRB. Growers may obtain greater animal production per hectare by interseeding winter cereals into bermudagrass than by monoculturing separate pastures.
