|Endecott, R -|
Submitted to: Western Section of Animal Science Proceedings
Publication Type: Proceedings
Publication Acceptance Date: April 10, 2009
Publication Date: June 15, 2009
Citation: Endecott, R.L., Waterman, R.C. 2009. USE OF A SELF-FED, SMALL-PACKAGE PROTEIN SUPPLEMENT FOR BEEF COWS POST-WEANING. Western Section of Animal Science Proceedings 60:326-365. Interpretive Summary: Low amounts of supplemental protein, particularly from sources high in ruminally undegradable protein (RUP), may enhance nitrogen utilization. A supplement composed of small quantities of high-RUP (> 70% of CP as RUP) ingredients combined with salt and minerals has previously demonstrated to maintain ruminal function with low quality forage and was consumed in controlled and consistent patterns by cows grazing desert range. In a 3-year field study in central New Mexico, gestating cows consuming a small-package, self-fed supplement (25% feather meal, 25% blood meal, and 50% mineral mix; < 250 g/d consumption) maintained BW and BCS during late fall and early winter, and had similar performance to cows hand-fed an oilseed-based supplement at > 454 g/d. The objective of this study was to evaluate the effectiveness of a self-fed small-package supplement for maintaining BW of post-weaning beef cows grazing native range in the Northern Great Plains. Strategic protein supplementation with a small-package, self-fed supplement did not impact cow performance. Target intakes of the mineral-protein mix were only achieved in 1 of 2 years, which may have contributed to the lack of response. Cows were able to select a high quality diet during both years due to low stocking rates. Cow body weight loss despite diet quality characteristics indicating adequate nutrient supply may be due to rapid temperature drops and inclement weather near the end of the experiment in both years. Further research identifying liming nutrients in range forages and the use of strategic small-package supplementation may be beneficial to optimize range livestock production.
Technical Abstract: A 2-year supplementation study conducted at Miles City, MT from mid-October to mid-December in 2007 and 2008 evaluated responses of beef cows (n = 141 in 2007, n = 138 in 2008; avg BW = 546 ± 5.2 kg) grazing dormant native range (8.8% CP, 64% NDF, 71% IVDMD) to two different supplementation strategies. Each year, cows were stratified by age and weight at weaning and then assigned to one of two supplements: 1) self-fed loose mineral mix (MIN) or 2) self-fed mineral plus high-bypass protein sources (MIN+PRO; 50% mineral mix, 25% feather meal, 25% fish meal). Target intakes were 70 g/d for MIN and 140 g/d for MIN+PRO. Cows were weighed and hip height and girth measurements were taken at the beginning and end of the 60-d studies. Weight-to-height and weight-to-girth ratio changes were calculated. Data were analyzed with supplement, cow age (2, 3, and 4+), year, and their interactions in the model. In 2007, cows fed MIN consumed 28 g/d and MIN+PRO cows consumed 93 g/d, which was lower than the target amount for both supplements. In 2008, MIN cows again failed to consume the target amount (13 g/d), while MIN+PRO cows consumed just over target amount (160 g/d). Cows lost similar (P = 0.70) amounts of weight during the study regardless of supplement treatment (-22 and -25 ± 5 kg for MIN and MIN+PRO, respectively). Likewise, weight-to-height ratio change (-0.25 and -0.25 ± 0.04) and weight-to-girth ratio change (-0.10 and -0.12 ± 0.02) were similar (P = 0.60) for MIN and MIN+PRO cows, respectively. Year × cow age interactions (P = 0.08) were observed for weight change and weight-to-height ratio change. Two- and 3-yr-old cows lost less weight in 2008 than in 2007, while mature cows lost similar amounts of weight in both years. All cows exhibited less change in weight-to-height ratio in 2008 compared to 2007, with the difference between years most pronounced in younger cows. Protein supplementation at this level did not impact cow performance; however, forage quality was higher than expected, which may have contributed to the lack of response to supplementation with the mineral-protein mix.