Interaction of feed intake level on comparative ruminal and total tract digestion of dry-rolled and steam-flaked corn

Abstract

Four Holstein steers (208 kg) with "T" cannulas in the rumen and proximal duodenum were used in a 4 x 4 Latin square design experiment to evaluate the interaction of feed intake level on comparative ruminal and total tract digestion of dry-rolled and steam-flaked corn. The basal diet contained (DM basis) 6% alfalfa hay, 6% sudangrass hay, 75% corn, 2% yellow grease, 5% cottonseed meal, 3% cane molasses, and 3% supplement. The corn portion of the diet was provided as either dry-rolled (density = .54 kg/L) or steam-flaked (density = .36 kg/L). Dry matter intake was restricted to allow for .64 vs 1.28 kg/d of weight gain (1.6 vs 2.4% of BW). Ruminal digestibility of OM, starch, and feed N were not affected (P > .10) by DMI. Postruminal digestion of OM and N and total tract digestibility of OM and DE decreased (P < .05) as DMI was increased. Total tract starch digestibility was not influenced (P > .10) by DMI. Steam flaking corn increased (P < .05) ruminal digestibility of OM and starch and postruminal and total tract digestibility of OM, starch, N, DE, and ME. Increasing DMI and steam flaking decreased (P < .05) ruminal pH and molar proportion of acetate. It is concluded that corn processing is the primary factor influencing site and extent of starch digestion. Decreasing DMI increases DE value of the diet; however, ME value is not affected because of increased energy loss as methane.

Effect of corn processing on starch digestion and bacterial crude protein flow in finishing cattle

“…However, several trials have been published, primarily from one laboratory, which compare DRC and SFC. Reported BCP flows range from similar (Zinn et al, 1995), to 13% greater (Barajas and Zinn, 1998), 28% greater (Zinn, 1990), and 31% greater for steers fed SFC compared with DRC-based diets. Bacterial CP efficiencies were similar between SFC and DRC in all of these trials except Zinn et al (1995), which reported a 14.2% lower BCP efficiency for SFC compared with DRC.…”

“…Reported BCP flows range from similar (Zinn et al, 1995), to 13% greater (Barajas and Zinn, 1998), 28% greater (Zinn, 1990), and 31% greater for steers fed SFC compared with DRC-based diets. Bacterial CP efficiencies were similar between SFC and DRC in all of these trials except Zinn et al (1995), which reported a 14.2% lower BCP efficiency for SFC compared with DRC. In our trial, steers fed SFC had greater (P < 0.05) ruminal OM degradation compared with DRC, but the bacterial N efficiency was numerically 6% lower resulting in equal BCP flow from the rumen.…”

Substituição do farelo de soja por uréia ou amiréia para vacas em final de lactação

“…O indicador externo utilizado para determinação da digestibilidade no trato digestivo total foi o óxido de cromo, colocado no rúmen através da cânula, na quantidade de 50 g/d em duas doses, do 5º ao 14º dia de cada período, considerando a quantidade como 0,4% da ingestão de matéria seca, em conformidade com Zinn et al (1995). Amostras das fezes foram colhidas nos quatro primeiros dias do período de colheita de dados, em intervalos de quatro horas, atrasando-se o horário em uma hora por dia para se ter amostragens em cada hora do dia.…”

Effects of ractopamine hydrochloride are not confined to mammalian tissue: Evidence for direct effects of ractopamine hydrochloride supplementation on fermentation by ruminal microorganisms1

“…Sindt et al [79] examined the impact of grain processing on ruminal fermentation and found that decreasing flake density from 360 or 310 g/L increased microbial efficiency (P < 0.05) and tended to increase microbial nitrogen flow to the duodenum (P < 0.10). Zinn et al [80] studied the impact of grain processing and dry matter intake on ruminal fermentation and found that steam-flaking corn increased (P < 0.05) ruminal digestion of organic matter and starch. Ruminal pH levels were lower and molar proportions of acetate were higher in steers with greater dry matter intake and for steers fed steam-flaked corn diets compared with steers fed dry-rolled corn (P < 0.05).…”