Evaluating internal and external markers versus fecal sampling procedure interactions when estimating intake in dairy cows consuming a corn silage-based diet

Abstract

Feed intake assessment is a valuable tool for herd management decisions. The use of markers, either internal or external, is currently the most used technique for estimating feed intake in production animals. The experiment used 10 multiparous Holstein cows fed a corn silage-based diet, with 55:45 forage-to-concentrate ratio, the average fecal recovery (FR) of TiO was higher than FR of CrO, and both FR were more than unity. With internal markers, acetyl bromide lignin and cutin FR were lower than unity, and average FR for indigestible neutral detergent fiber (iNDF) and indigestible acid detergent fiber (iADF) was 1.5. The FR was unaffected by the fecal sampling procedure and appears to be an intrinsic property of each molecule and how it interacts with digesta. Of the 2 external markers, only CrO produced accurate fecal output (FO) estimates and the same happened to dry matter digestibility (DMD) when iNDF and iADF were used. Estimates for DMD and FO were affected by sampling procedure; 72-h bulk [sub-sample from total feces collection (TFC)] sampling consistently produced accurate results. The grab (sub-samples taken at specific times during the day) sampling procedures were accurate when using either of the indigestible fibers (iNDF or iADF) to estimate DMD. However, grab sampling procedures can only be recommended when concomitant TFC is performed on at least one animal per treatment to determine FR. Under these conditions, CrO is a suitable marker for estimating FO, and iNDF and iADF are adequate for estimating DMD. Moreover, the CrO+iADF marker pair produces accurate dry matter intake estimates and deserves further attention in ruminant nutrition studies. The method of dosing the external markers is extremely important and greatly affects and determines results. Whichever the method, it must allow the animals to display normal feeding behavior and not affect performance. The grab sampling procedures can replace TFC (once FR is established), which may open new possibilities for pasture-based or collectively housed animals.

Effect of using Acacia mearnsii tannin extract as a feed additive on nutritional variables and productive performance in dairy cows grazing a temperate pasture

“…Moreover, both fecal output and herbage intake were estimated by double marker technique using Cr 2 O 3 and iNDF as markers, respectively, which are also reported to have bias associated to herbage and fecal sampling protocol and marker recovery in feces (Guinguina, Ahvenjärvi, Prestløkken, Lund, & Huhtanen, 2019;Velásquez et al, 2018).…”

Incremental amounts of rumen-protected histidine increase plasma and muscle histidine concentrations and milk protein yield in dairy cows fed a metabolizable protein-deficient diet

“…This suggests that NDF digestibility may have been overestimated by 23 percentage units when using iADF as the internal marker. Nevertheless, our sampling protocol resulted in 8 fecal grab samples per cow over a 3-d period, thus following literature recommendations for improved estimation accuracy of nutrient digestibility in the total gastrointestinal tract (e.g., Sampaio et al, 2011;Morris et al, 2018;Velásquez et al, 2018).…”

“…However, the total-tract digestibilities of NDF (mean = 65.6%) and ADF (mean = 68.4%) appear to be overestimated possibly because of uncertainties associated with the adoption of iADF as the internal marker to estimate fecal output of DM. Recently, Velásquez et al (2018) reported that the fecal recoveries of iADF av- eraged 147% with 2 fecal grab sampling procedures and 153% with a pooled sample obtained over 3 d of total collection in Holstein cows fed a corn silage-based diet. Fecal recovery greater than 100% can underestimate fecal DM output, resulting in overestimation of apparent total-tract fiber digestibility.…”

Uso de traçadores para a determinação de consumo, seleção e digestibilidade de dietas de ovinos compostas por gramíneas e leguminosas

“…Funcionalmente, os marcadores são classificados como sendo internos, aqueles que ocorre naturalmente nos alimentos, ou externos, aqueles adicionados ao alimento ou dosados separadamente ao animal (LIPPKE, 2002). Os marcadores externos têm sido usados para estimar a produção fecal e marcadores internos para estimar a digestibilidade da matéria seca (VELÁSQUEZ et al, 2018).…”

“…Um marcador para ser ideal deve apresentar características essenciais como, não ser absorvido pelo animal, recuperação completa após a ingestão, não ter efeito sobre o animal, não afetando e nem sendo afetado pelo trato gastrintestinal, ter características físicas (em termos de tamanho de partícula e densidade) semelhantes ao conteúdo do trato digestivo, estando intimamente associado ao material marcado, com taxa de passagem semelhante ao alimento e medição quantitativa precisa, com método de estimativa simples e específico MAYES, 2006;VELÁSQUEZ et al, 2018).…”