Impact of high-energy diets on the rumen environment and digital cushion in confined cattle

Abstract

This study aimed to identify gross and microscopic changes, caused by high-energy diets, in the rumen environment and hoof of confined beef cattle. The study sample comprised 40 confined heifers (Bos taurus) with no disease history divided into four experimental groups using different diets: Group 1 (D1, control), 48:52 forage:concentrate ratio; Group 2 (D2), 30:70 forage:concentrate ratio; Group 3 (D3), 30:70 forage:concentrate ratio + sucrose; Group 4 (D4), 100% concentrate. All animals underwent clinical examination, assessment of ruminal fluid pH and lameness, and sample collection after slaughter for histopathology of the hoof laminae and digital cushion and ruminal tissue. All dependent variables of the study were compared using the SPSS 20.0 statistical software. The variables that did not show normality (HR, RM, ST, and CRT) were compared with application of the Kruskal-Wallis test followed by the Dunnet’s multiple comparison test. All other variables were submitted to analysis of variance (ANOVA) followed by Tukey’s test. The different diets had an impact on the rumen environment (p<0.05) of the heifers assessed, with momentary general depression in the first 12 h after sucrose induction (D3), as well as mild clinical signs in D4. The animals in D3 and D4 presented lower motility (p<0.05) and ruminal pH (p<0.01) than those in D1. Of the 40 heifers, 27.5% (n=11) showed gross lesions in the epithelium of ruminal pillars, whereas 22.5% (n=9) of those in D3 and D4 presented these lesions. Sole corium thickness varied between heifers in D3 compared with those in D1 and D2 (p<0.05). Therefore, high-energy diets, as used in this study, alter some clinical parameters and the rumen environment, causing lesions in the rumen mucosa, and of lesser intensity, in the hoof corium and laminae, suggestive of laminitis.

Impact of Nutrients on the Hoof Health in Cattle

“…Laminitis may appear as a primary condition, but it is more often secondary to rumen acidosis [ 9 , 10 , 15 , 42 , 81 , 86 , 87 , 88 , 89 , 90 , 91 ], in which the risk of lameness increases [ 26 , 66 , 71 , 92 ]. Fructans and glucose have been shown to increase lactic acid production, thereby increasing the risk of laminitis [ 93 ].…”

“…Farmers often try to compensate for this deficiency by feeding more concentrated feed with easily digestible forms of carbohydrates, which increases the energy value of the feed [ 94 , 95 ]. The administration of concentrated feed increases the production costs and improves animal production, because it increases daily weight gain and shortens fattening time [ 87 ]. As carbohydrates increase, fiber, saliva production, and chewing time decrease in the feed, and consequently the rumen pH decreases [ 26 , 27 , 35 , 42 , 94 ] due to the higher concentration of lactic acid produced by bacteria [ 9 , 26 , 40 ].…”

“…The differences in the proportion of starch in the feed ration of cattle may promote rumen damage with systemic adverse effects on other tissues, including the digital cushion, which is associated with pathologies that occur in the joint and laminar tissue. These structural changes in the hoof can predispose the animal to lameness and the development of hoof injuries, leading to economic losses [ 12 , 87 ]. In cows with laminitis that were fed a highly concentrated feed ration, a lower layer of fat on the heel was observed [ 87 ].…”

“…These structural changes in the hoof can predispose the animal to lameness and the development of hoof injuries, leading to economic losses [ 12 , 87 ]. In cows with laminitis that were fed a highly concentrated feed ration, a lower layer of fat on the heel was observed [ 87 ].…”

“…When compared to roughage, the highly concentrated feed ratio increases the expressions of interleukin-1β, interleukin-6, tumor necrosis factor α, and MMP-2 mRNA in lamellar tissues. The change in the composition and function of bacteria in the rumen that is caused by concentrated feed leads to higher levels of lipopolysaccharide in the peripheral blood and it can further activate the inflammatory response in the lamellar tissue and even cause laminar damage [ 26 , 81 , 86 , 87 ]. Lipopolysaccharide is a significant contributor to damage and local inflammation in the capillaries of the lamellae in the hoof [ 86 ], thereby disrupting the production of quality horn [ 26 ].…”