Inorganic Versus Complexed Trace Mineral Supplements on Performance of Dairy Cows1

Professional Animal Scientist, Feb 2004 by Kincaid, R L, Socha, M T

Abstract

To determine the effects of chemical form of trace mineral supplements on performance of dairy cows, Holstein cows (n = 36) were assigned to dietary treatments of inorganic trace minerals or a combination of inorganic and completed trace minerals (CTM). Starting at 21 d prepartum, dry cows were fed hay and a grain supplement that contained one of the trace mineral supplements. Cows continued to receive their respective trace mineral treatment from parturition until 150 d in milk (DIM). Cows fed the CTM lost less BW prepartum (P

(Key Words: Cows, Inorganic Trace Minerals, Complexed Trace Minerals, Supplements.)

Introduction

Nutritional deficiencies of Zn, Cu, and Co reduce ADG and DMI of ruminants (McDowell, 1992). In a study to separate the effects of trace element deficiencies on DMI and feed efficiency, Miller et al. (1965) used a restricted-fed control group to demonstrate that Zn deficiency per se lessened feed efficiency of calves. Trace elements also can interact with other nutrients to produce associative effects on animals. For example, dietary protein restriction reduced Zn absorption and retention in calves (Stake et al., 1973). Hatfield et al. (1995) obtained greater (P

When intakes of many trace elements are low, homeostatic control mechanisms increase the intestinal absorption efficiency for the trace element (Miller, 1975). For example, Neathery et al. (1973) reported that cows fed diets low in Zn (16.6 ppm) had a net absorption of Zn of 53% compared with 35% Zn absorption in cows fed diets with 39.5 ppm of Zn. Studies that have compared the intestinal absorption efficiency and tissue retention of inorganic and organic trace elements have reported both similar (Yost et al., 2002; Miltimore et al., 1978 ) and greater absorption of trace elements from organic compared vs inorganic forms (Stanton et al., 1998; Rabiansky et al., 1999) depending upon the presence of antagonists to absorption (Kincaid et al., 1986), use of growth implants (Huerta et al., 2002), and age of the cattle (Kincaid et al., 1997). Other factors that affect response to organic trace minerals may include the particular trace element, binding affinity between the trace element and chelating agent, and the dietary concentration of the trace element.

Ballantine et al. (2002) reported increased milk yield in cows fed a combination of complexed trace minerals (CTM) and sulfate forms of trace minerals. However, an explanation of the biological basis for an increase in milk yield is unclear, and more work is needed. Thus, the objective of this study was to compare inorganic trace mineral supplements and supplements containing a combination of inorganic and organic trace minerals on feed intake, milk production, measures of milk production efficiency, and blood metabolites in lactating dairy cows.

Materials and Methods

The protocol for this experiment was approved by the WSU Animal Care and Use Committee. Multiparous Holstein cows (n = 36) were randomly assigned to diets supplemented with either inorganic trace minerals or to diets supplemented with a combination of inorganic minerals and CTM (Cu, Zn, Mn, and Co). Cows were vaccinated with J-5® (E. coli; Pharmacia Animal Health, Exton, PA) and Triangle 4® (killed IBR, PI^sub 3^, and BRSV; Pharmacia Animal Health). At 21 d before their expected calving date, cows were assigned to prepartum diets of grass hay provided free choice and were individually fed 3.3 kg/d (DM basis) of concentrate to provide treatment supplements of trace elements. The concentrate was composed of 82.3% ground corn, 10% soybean meal (44% CP), 4% molasses, 1.5% iodized salt, 1% trace mineral premix (Table 1), 0.5% limestone, 0.2% magnesium oxide, 0.1% vitamin D premix (8810 IU/g), 0.025% vitamin A premix (30,000 IU/g), 0.2% Se premix (200 mg/kg Se as Na selenite), 0.1% vitamin E premix (500 lU/g), and 0.05% pellet binder. Based upon chemical analysis of the hay and concentrates (Table 2), the 3.3 kg/d of concentrate and an estimated hay intake of 9.1 kg/d provided daily prepartum intakes of 148 mg of Cu, 856 mg of Zn, 660 mg of Mn, and 23 mg of Co.

Postpartum cows were fed a lactation total mixed ration (TMR) formulated to provide a trace mineral supplement of either inorganic or a combination of inorganic and organic sources. The lactation TMR (Table 3) consisted of alfalfa hay and haylage, whole cottonseeds, wheat mill run, and concentrate. The ingredient composition of the trace mineral premixes is provided in Table 4, and the chemical composition of the TMR is given in Table 5. Cows were individually fed via Calan head gates and were fed their dietary treatment until 150 d in milk (DIM).

Daily DMI were recorded for lactating cows, and samples of the TMR were taken weekly and composited by month. Cow BW and BCS were taken monthly. Blood samples were collected into heparinized and non-heparinized vacutainers on d -21, 0, 28, and 150 relative to parturition. Immediately postpartum, a sample of colostrum was collected. Milk yields were recorded daily, and samples of a.m./p.m. milk were taken monthly for analysis of major components by the regional Dairy Herd Improvement Association (DHIA) laboratory (Burlington, WA). Samples of serum, whole blood, colostrum, and milk were frozen until analysis.