The effects of amount of whole barley, barley bulk density, and form of roughage on feedlot lamb performance, carcass characteristics, and digesta kinetics.

Abstract

We conducted two feedlot trials and one metabolism trial to evaluate the effect of barley level, barley bulk density, and physical form of roughage on lamb growth performance and digesta kinetics. Level of whole barley (50, 70, 90%) and type of roughage (chopped or pelleted alfalfa) were evaluated in Trial 1 (50 d period). Trial 2 (50 d) evaluated barley bulk density (heavy = 671 and light = 607 kg/m3), form of roughage (pelleted or chopped alfalfa), and level of barley (80 or 40%). The influence of treatments used in Trial 2 on digesta kinetics was evaluated in Trial 3. Gain:feed increased and DMI decreased (P < .10) linearly with increasing level of barley, and ADG and DMI were greater (P < . 10) for lambs fed pelleted vs chopped alfalfa in Trial 1. The 70% barley diet produced the highest yield grade and kidney-pelvic fat and the lowest leg score among barley levels (P < .10). Lambs fed pelleted alfalfa had heavier carcasses and a thicker body wall than lambs fed chopped alfalfa (P < .02). In Trial 2, DMI was less and gain:feed greater (P < .01) for lambs fed the heavy barley than for lambs fed the light barley and for the 80% barley diet compared to the 40% barley diet. Lambs fed pelleted alfalfa had greater dressing percentages than lambs fed chopped alfalfa. Backfat and body wall thickness were greater (P < .10) for lambs fed the 80% barley diet than for those fed the 40% barley diet. In Trial 3, retention time of barley was greater (P < .10) for lambs fed light rather than heavy barley, and retention time of alfalfa was greater (P < .10) for lambs fed chopped compared with pelleted alfalfa. Acetate:propionate ratio was greater (P < .10) for lambs fed light vs heavy barley and lambs fed the 40 vs 80% barley diets. Ruminal pH was lower (P = .05) and in situ barley digestion greater (P = .03) over time in lambs fed the 80% barley diet than in lambs fed the 40% barley diet. Feedlot lamb ADG was not always greatest with high levels of barley; however, gain:feed improved at the higher barley levels. The higher barley levels seemed to result in fatter lambs.

Canola screenings as a fiber source in barley-based feedlot diets: effects on rumen fermentation and performance of steers

“…Increasing the level of barley in the diet resulted in a linear increase (P < 0.05) in total VFA levels at 1000 and 1400 h (Table 3). Our results are consistent with other studies which showed reduced ruminal pH and increased total VFA levels as the amount of rapidly fermented carbohydrate from barley grain in the diet increased (McAllister et al 1990;Feng et al 1995;Hatfield et al 1997).…”

“…This resulted in a lower (P < 0.05) acetate:propionate ratio for the barleybased diets. These results are in agreement with other researchers who reported similar responses for molar proportions of ruminal acetate and propionate to increased levels of readily fermentable carbohydrates in the diet (Hatfield et al 1997;Reinhardt et al 1997). The observed changes in molar ratios of acetate:propionate are related to a decline in ruminal pH after feeding to or below 5.5, as a result of bar- For personal use only.…”

“…Propionate is also the primary precursor for glucose metabolism in ruminants (Brockman and Laarveld 1986). The results of the present study agree with recent research (Zinn et al 1994;Hatfield et al 1997) where improved efficiencies were reported in cattle fed higher levels of cereal grains as compared with forage diets. In the current study, replacement of canola screenings with barley yielded higher dietary levels of readily soluble carbohydrates providing greater yields of propionate for ruminal fermentation.…”

Níveis de feno de alfafa e forma física da ração no desempenho de cordeiros em creep feeding

“…Os autores sugerem que os cordeiros que receberam ração no sistema livre escolha ingeriram menos concentrado, resultando em menor acidose. HATFIELD et al (1997), ao compararem alfafa peletizada e moída, não verificaram diferenças no desempenho dos cordeiros, porém aqueles que receberam alfafa moída apresentaram maior taxa de amido fecal.…”

“…Assim, a suplementação dos cordeiros lactentes afirma-se como uma prática de manejo prioritária e estratégica na produção de cordeiros, devendo ser iniciada logo após o nascimento, com a finalidade de adaptar os animais ao consumo de alimento sólido. Além disso, a qualidade da fibra torna-se um fator importante na dieta, tendo em vista que os cordeiros são mais suscetíveis à acidose aguda, quando comparados aos bovinos (HATFIELD et al, 1997).…”