Effect of source of trace minerals in either forage- or by-product–based diets fed to dairy cows: 1. Production and macronutrient digestibility

Abstract

Excess rumen-soluble Cu and Zn can alter rumen microbial populations and reduce fiber digestibility. Because of differences in particle size and chemical composition, ruminal and total-tract digestibility of fiber from forage- and by-product-based diets can differ. We hypothesized that, because of differences in mineral solubility, diets with hydroxy rather than sulfate trace minerals would have greater fiber digestibility, but the effect may depend on source of fiber. Eighteen multiparous cows were used in a split-plot replicated Latin square with two 28-d periods to evaluate the effects of Cu, Zn, and Mn source (sulfates or hydroxy; Micronutrients USA LLC, Indianapolis, IN) and neutral detergent fiber (NDF) source (forage diet = 26% NDF vs. by-product = 36%) on total-tract nutrient digestibility. During the entire experiment (56 d) cows remained on the same fiber treatment, but source of supplemental trace mineral was different for each 28-d period so that all cows were exposed to both mineral treatments. During each of the two 28-d periods, cows were fed no supplemental Cu, Zn, or Mn for 16 d followed by 12 d of feeding supplemental Cu, Zn, and Mn from either sulfates or hydroxy sources. Supplemental minerals for each of the mineral sources fed provided approximately 10, 35, and 32 mg/kg of supplemental Cu, Zn, and Mn, respectively, for both fiber treatments. Total dietary concentrations of Cu, Zn, and Mn were approximately 19, 65, and 70 mg/kg for the forage diets and 21, 85, and 79 mg/kg for the by-product diets, respectively. Treatment had no effect on dry matter intake (24.2 kg/d) or milk production (34.9 kg/d). Milk fatty acid profiles were altered by fiber source, mineral source, and their interaction. Cows fed the by-product diets had lower dry matter (65.9 vs. 70.2%), organic matter (67.4 vs. 71.7%), and crude protein digestibility (58.8 vs. 62.1%) but greater starch (97.5 vs. 96.3%) and NDF digestibility (50.5 vs. 44.4%) compared with cows fed the forage treatment. Feeding increased concentrations of by-products decreased total digestible nutrients regardless of mineral source. Feeding hydroxy Cu, Zn, and Mn increased NDF digestibility (48.5 vs. 46.4%) but had no effect on total digestible nutrients.

Chlorellavulgaris microalgae and/or copper supplementation enhanced feed intake, nutrient digestibility, ruminal fermentation, blood metabolites and lactational performance of Boer goat

“…Contrary to the present results, Faulkner and Weiss (2017) reported no effect on nutrient digestibility with Cu supplementation to dairy cows.…”

“…As indicated in many reviews, increasing Cu levels above animal requirement can have some positive effects on lactational performance (quantity and composition) and oxidative status of dairy cattle (Overton & Yasui, 2014). Some previous studies (Faulkner & Weiss, 2017;Formigoni et al, 2011) showed that supplementing diets with trace minerals did not affect productive and reproductive performance of lactating cows. However, Roshanzamir, Rezaei, and Fazaeli (2020) reported that supplementing lactating cows with trace minerals such as Cu had positive effects on DM intake and digestibility, lactational performance, somatic cell counts and milk total antioxidant capacity.…”

Trace mineral source influences ruminal distribution of copper and zinc and their binding strength to ruminal digesta1,2,3

“…The greater solubility of Cu and Zn from STM may alter microbial fermentation in cattle. Faulkner and Weiss (2017) recently reported lower NDF digestibility in lactating dairy cows supplemented with STM compared with those supplemented with HTM. The stronger binding of STM, relative to HTM, to the solid rumen digesta fraction may also reduce their bioavailability in the small intestine of cattle.…”

“…In vitro studies have indicated that Zn and Cu can adversely affect fiber digestion (Durand and Kawashima, 1980). Lactating dairy cows supplemented with HTM had greater (51.2% vs. 49.8%) NDF digestibility than cows supplemented with similar concentrations of STM (Faulkner and Weiss, 2017). In the current experiment, an a priori power calculation was conducted to determine the number of animals need for this experiment.…”

“…Greater soluble concentrations of Cu and Zn in the ruminal environment can decrease fiber digestion in the rumen (Durand and Kawashima, 1980). Faulkner and Weiss (2017) recently reported that dairy cows supplemented with hydroxy TM (HTM) had greater NDF digestibility than those supplemented with sulfate TM (STM) sources. Therefore, our working hypothesis was that utilizing HTM would result in lower soluble TM concentrations in the rumen, thus affecting fermentation and mineral interactions differently from sulfate sources.…”