Effects of Pre-breeding Administration of Injectable Trace Mineral Supplements on Subsequent Reproductive Performance in Beef Herds

Final report for GNC15-202

Project Type: Graduate Student
Funds awarded in 2015: $10,000.00
Projected End Date: 08/31/2018
Grant Recipient: North Dakota State University
Region: North Central
State: North Dakota
Graduate Student:
Faculty Advisor:
Dr. Carl Dahlen
North Dakota State University
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Project Information

Summary:

The purpose of this project was to evaluate the effects of an injectable trace mineral supplement administered prior to breeding on reproductive parameters including pregnancy rates, calving distribution, and calf weaning weights. A total of 5 commercial beef cattle operators were selected by their local North Dakota State University county extension agents to participate in this research effort. Prior to involvement, telephone conversations were had with each producer to explain project details, detail producer involvement, and answer any questions. Within herd at each location, cows were stratified by days postpartum, then randomly assigned to receive one of two treatments: 1) Cows received no additional treatments prior to bull turnout (CON; n = 755) or 2) Cows were administered an injectable trace mineral supplement (60, 10 and 15 milligrams per milliliter (mg/mL) of zinc, manganese and copper as disodium EDTA chelates, and 5 mg/mL of selenium as sodium selenite) subcutaneously 30 d before bull turnout (TM; n = 764). On the day of mineral administration, blood samples were collected from a random sample of females (n = 46; 8 to 10 females per herd) immediately prior to mineral injection via jugular venipuncture and were analyzed for baseline mineral status. Total mixed rations were collected for the animals still in confinement prior to pasture/bull turnout and water samples were collected from all available water sources for each herd.

Cooperating producers beginning the project in Year 1 (2015) included Thorne Ranch, Watford City, ND, Hoff Ranch, Dickenson, ND, Schultz Ranch, Sheldon, ND, Ruland Ranch, New Town, ND. Year 2 (2016) included Roise Ranch, Powers Lake, ND.

Preliminary results from Year 1 were completed by late 2016/early 2017, whereas results from Year 2 were collected by late 2017/early 2018. Results indicated that there was no difference (P = 0.29) in the pregnancy rates of females between groups (TM: 91.1% and CON: 93.2%). Weaning weights of calves on the side of cows receiving treatments also were similar (P = 0.90), and mean calving date was not different (P = 0.99) for those calves born from ITM cows or CON cows. When evaluating the distribution of calves born in the calving season by 21-d increments, the proportion of calves born in the first 21, 22 to 42, or more than 42 d of the calving season were similar (P = 0.40) between groups.

Blood, feed, and water samples were collected. No differences (P = 0.11) were observed in the blood mineral levels between treatments for cobalt, copper, iron, manganese, molybdenum, selenium, or zinc before treatment administration.

Project Objectives:

Introduction:

Reproductive performance and superior overall herd health are vital to a successful and profitable cow herd. Deficiencies of trace minerals can lead to anemia, immune suppression, reduced ovulation, irregular estrous cycles, fetal malformations, and abortions, as trace minerals are vital to fetal development and nutrient transfer (Hostetler et al., 2003). Increased reproductive failure and herd death loss could result in decreased profitability for cattle producers.

The foundation of grazing beef cattle diets consists of roughly 85% forage, however not all nutrients can be obtained from forage alone (Greene, 2000). The National Research Council (NRC) has established requirements for successful animal production, based on ongoing research, for most minerals thought to be essential in beef cattle diets. If not found in feedstuffs, minerals should be supplemented to influence immunity, reproduction, and weight gain (Lalman and McMurphy, 2004). Mineral composition of forages, types of supplementation and individual animal intake of mineral supplementation are highly variable. Additionally, palatability, individual requirements, mineral content of available water sources, and season of year are all factors that must be considered when evaluating the consumption of mineral supplements as each is a factor affecting intake of minerals (McDowell, 1996).

Injectable trace mineral products are currently available and may be used for a more targeted supplement delivery. Injectable mineral products are, however, not blanket nutrients or broad spectrum, but contain only a few trace minerals: copper, manganese, selenium, and zinc. The label of injectable trace mineral products explicitly states that they are NOT a mineral replacement product and that other sources of mineral should be available to cattle. Injectable mineral supplements currently available are labeled as a source of zinc, manganese, selenium, and copper to be administered four weeks before calving and four weeks before breeding in beef cows (Multimin 90, USA). Particular minerals involved in reproductive performance and growth include but are not limited to copper, manganese, selenium and zinc (Hostetler et al., 2003). Copper is required for red blood cell formation and regulation, manganese for fetal bone formation, and selenium and zinc are required for protection from free radicals and involved in muscle generation (Hostetler et al., 2003).

Injectable supplementation advantages include the targeted delivery of known trace mineral elements. When growing heifers were administered half of the manufacturers recommended dose of trace mineral supplement, at three different time points, no differences were observed in age at puberty or attainment of pregnancy (Arthington et al., 2014). In contrast, when trace mineral injections were administered 30 d before calving and 30 d before breeding with the addition of an artificial insemination (AI) breeding system, a greater proportion of those females receiving the injectable supplement became pregnant to AI compared with cows not receiving injectable supplement (60.2 percent and 51.2 percent, respectively; Mundell et al., 2012).

To date, few studies have evaluated the use of injectable mineral supplements administered before breeding while utilizing a natural service breeding system on commercial beef operations. Data currently available regarding injectable trace mineral supplements are conflicting with regards to their effect on pregnancy attainment, weaning weights and calving distribution. Therefore, the objective of this study was to evaluate blood mineral levels before treatment administration on a subset of cows as well as evaluate the effects of injectable trace mineral supplements administered 30 d before the start of the breeding season on pregnancy rates, calf weaning weights, and calving distributions.

Objectives:

  • Document the effects of trace mineral supplements on reproductive performance in commercial beef herds.
  1. Protocol
    1. One thousand five-hundred nineteen postpartum commercial beef cows (Herd 1: n = 146; Herd 2: n = 501; Herd 3: n = 460, Herd 4: n = 204, and Herd 5: n = 132) were stratified within herd by d postpartum, then randomly assigned to receive one of two treatments: 1) Cows received no additional treatments prior to bull turn out (CON; n = 755); or 2) Cows were administered 6 mL of an injectable trace mineral supplementation (60, 10, and 15 mg/mL of zinc, manganese, and copper, as disodium EDTA chelates, and 5 mg/mL of selenium as sodium selenite) subcutaneously on d -30 relative to bull turn out (TM; n = 764).
    2. Natural service bulls were turned out to all cows 30 d after treatment administration and remained with cows for the duration of the producer defined breeding season. Transrectal ultrasonography or rectal palpation was used to determine the presence of a viable fetus at least 30 d after the end of the breeding season by a herd veterinarian. Calf weaning weights were collected at the time of weaning for the year of administration to determine if any effects of injectable trace mineral supplementation administered to the cow affected the weight of the calf at her side. At the time of calving, birth date and calf sex were recorded.
  2. Results
    1. Analysis of data indicate that pregnancy rates did not differ (P = 0.29) between groups of females in the CON and TM groups. Weaning weights of calves on the side of cows receiving treatments also were similar (P = 0.90). At calving, mean calving date was not different (P = 0.99) for those calves born from TM cows or control cows. When evaluating the distribution of calves born in the calving season by 21-d increments, the proportion of calves born in the first 21, 22 to 42, or more than 42 d of the calving season were similar (P = 0.40) between groups.

 

  • Increase producer, extension personnel, and veterinarian knowledge and awareness of mineral status, around the state of North Dakota, generated by the interpretation and reports of the baseline mineral samples.
    1. Protocol
      1. On d -30 relative to bull turnout, blood samples were collected from a subset of eight to 10 cows within each herd. Blood was collected via jugular venipuncture for analysis of baseline mineral status. Blood samples were analyzed for concentrations of cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), Molybdenum (Mo), selenium (Se), and zinc (Zn).
      2. Samples of total mixed rations were collected and placed in bags for herds 3 and 4 while supplemented hay samples were collected for herd 1, representing the animals still in confinement prior to pasture/bull turn out. Water samples were also collected from any and all available water sources for each herd.
    2. Results
      1. Blood, feed, and water samples were collected at each operation. No differences (P = 0.11) were observed in the blood mineral levels between treatments for cobalt, copper, iron, manganese, molybdenum, selenium, or zinc before treatment administration. Since blood was collected before treatment administration, results are as anticipated. Herd blood values averages, water samples, and feed samples values are included in the following tables.

 

  • Measure the change in management considerations (i.e. changes in mineral supplementation, use of injectable products, etc.), and the quality of life of those cooperating producers.
    1. Protocol
      1. These measurements will be evaluated with the use of survey based questionnaires focusing on learning and behavior based evaluations. Surveys will include before and after type questions as well as assessments of actions or management strategies employed after year one of the project is complete. Producers will be the targeted audience for this type of evaluation as the producers may likely have the ability to increase profitability.
    2. Progress
      1. Survey questions are in the process of being created for distribution to cooperating producers.

 

Cooperators

Click linked name(s) to expand
  • Carl Dahlen
  • Kurt Froelich
  • Karla Ryan

Research

Materials and methods:

All cattle were managed according to the Federation of Animal Science Guide for the Care and Use of Agricultural Animals in Agriculture Research and Teaching (FASS, 1999). All procedures were reviewed and approved by the Institutional Animal Care and Use Committee of North Dakota State University.

Treatments and Sampling

Four North Dakota State University extension agents from varying geographical locations throughout the state of North Dakota were recruited to identify a commercial beef producer in their area for participation in this experiment. Selection of producers was based on a history of good record keeping and commitment to all phases of the proposed research. Expectations of cooperating producers included assisting with data collection and record keeping for their operation. Each herd (1-5) was managed individually and management decisions were made by each producer.

One thousand, three hundred and eleven postpartum beef cows (Herd 1: n = 146; Herd 2: n = 501; Herd 3: n = 460, Herd 4: n = 204, and Herd 5: n = 132) were stratified within herd by d postpartum, then randomly assigned to receive one of two treatments: 1) Cows received no additional treatments prior to bull turn out (CON; n = 755); or 2) Cows were administered 6 mL of an injectable trace mineral supplement (60, 10, and 15 mg/mL of zinc, manganese, and copper, as disodium EDTA chelates, and 5 mg/mL of selenium as sodium selenite) subcutaneously on d -30 relative to bull turn out (ITM; n = 764).

On d -30 relative to bull turnout, blood samples were collected from a subset of eight to 10 cows within each herd. Blood was collected via jugular venipuncture in 10-mL Vacutainer tubes (BD Worldwide, Franklin Lakes, NJ) for analysis of baseline mineral status. Blood samples were immediately placed on ice and allowed to clot for a minimum of 12 hrs. Blood samples were then centrifuged 1,200 x g for 20 min with plasma collected and stored at -20°C in a commercial freezer. Blood samples were analyzed for concentrations of cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), Molybdenum (Mo), selenium (Se), and zinc (Zn; Table 6.1.) via inductively coupled plasma-mass spectrometry (ICP-MS) by Michigan State University Diagnostic Center for Population and Animal Health (MSU-DCPAH; East Lancing, MI). Plasma samples were diluted 20-fold with a 0.05% EDTA and Triton X-100, 1% ammonium hydroxide, 2% propanol and 20 ppb of scandium, rhodium, indium and bismuth solution (Wahlen et al., 2005). Concentrations of minerals were calibrated using a 4-point linear curve from the analyte-internal standard response ratio. The lowest identifiable concentrations for each mineral was 0.1 ug/mL for copper and zinc, 0.5 ng/mL for manganese, and 0.1 ng/mL for cobalt, molybdenum, and selenium. Plasma concentrations of iron were analyzed using an Olympus iron kit, utilizing TPTZ [2,4,6-Tri-(2-pyridyl)-5-triazine] as the chromogen.

Samples of total mixed rations were collected and placed in bags for herds 3 and 4 while supplemented hay samples were collected for herd 1, representing the animals still in confinement prior to pasture/bull turn out. Feed samples were collected and dried overnight in a 100 degree °C oven, and samples were sent to MSU-DCPAH for analysis via ICP-MS. The control diet utilized was the NIST3 Typical Diet. Feed sample results are listed in Table 1. Water samples were also collected from any and all available water sources for each herd, chilled, and also sent to the MSU-DCPAH for analysis via ICP-MS. Water sample results are illustrated in Table 2.

Table 1. Mineral composition of feed samples1

 

Mineral Requirements2

Rec. Maximum Levels3

Herd4

Mineral

1

3

4

Aluminum

-

-

51.5

681.8

824.4

Antimony

-

-

< 5.0

< 5.0

< 5.0

Arsenic

-

-

< 2.5

< 2.5

< 2.5

Barium

-

-

32.4

35.2

42.2

Boron

-

-

5.7

14.5

9.5

Cadmium

-

-

< 0.3

< 0.3

< 0.3

Calcium

-

-

3436

14.5

3794

Chromium

-

1,000.00

< 1.0

4.9

1.4

Cobalt

0.15

25.00

< 0.50

0.53

< 0.50

Copper

10.00

40.00

4.2

20.5

6.1

Iron

50.00

500.00

225

965

917

Lead

-

-

< 2.5

< 2.5

< 2.5

Magnesium

1,200-2,000

4,000

1583

3167

2276

Manganese

40.00

1,000.00

63.1

134.9

71.5

Mercury

-

-

< 10.0

< 10.0

< 10.0

Molybdenum

-

5.0

3

< 1.0

1

Phosphorus

-

-

1928

2747

1685

Potassium

600-700

20,000

22714

12684

16051

Selenium5

0.10

5.00

< 10.0

< 10.0

< 10.0

Sodium

600-1,000

-

< 50

787

463

Sulfur

1,500

3,000-5,000

1095

2210

1568

Thallium

-

-

< 12.5

< 12.5

< 12.5

Zinc

30.00

500.00

10.5

53.2

20.7

1Mineral results are reported as ppm

2, 3Adapted from National Research Council (NRC). Nutrient requirements of beef cattle. 8th (revised) edition. Washington, DC. National Academy Press. 2016. p. 110.

4Herds 1, 3, and 4 are represented. Herd 2 cattle were on grass pasture at least 1 month prior to treatment administration.

5Labrotory sensitivity not adequate to detect differences in feed samples

Table 2. Mineral composition of water samples1

 

 

 

Herd

 

Mineral

Rec. Maximum Levels2

1a

1b

2a

3

4

 

5

Aluminum

< 5.0

< 0.05

< 0.05

0.31

0.53

< 0.25

< 0.05

Antimony

-

< 0.006

< 0.006

< 0.25

< 0.25

< 0.25

< 0.006

Arsenic

< 0.05-0.2

< 0.10

< 0.10

< 0.25

< 0.25

< 0.25

< 0.10

Barium

< 1.0

< 2.0

< 2.0

0.053

0.356

< 0.025

< 2.0

Boron

< 5.0-3.0

.

.

0.33

0.06

0.36

.

Cadmium

< 0.05

< 0.005

< 0.005

< 0.025

< 0.025

< 0.025

< 0.005

Calcium

< 1,000

.

.

73.34

131.08

68.49

.

Chromium

< 0.1

< 0.10

< 0.10

< 0.05

< 0.05

< 0.05

< 0.10

Cobalt

< 0.1

.

.

< 0.025

< 0.025

< 0.025

.

Copper

< 0.5

< 1.3

< 1.3

< 0.025

0.031

< 0.025

< 1.3

Iron

< 0.4

< 0.30

< 0.30

0.4246

1.404

3.429

< 0.03

Lead

< 0.05-0.1

< 0.015

< 0.015

< 0.10

< 0.10

< 0.10

< 0.015

Magnesium

< 90-250

.

.

49.072

36.457

30.109

.

Manganese

< 0.05

< 0.05

< 0.085

0.141

0.716

0.051

0.42

Mercury

< 0.003-0.01

< 0.002

< 0.002

< 0.50

< 0.50

< 0.50

< 0.002

Molybdenum

< 0.06

.

.

< 0.10

< 0.10

< 0.10

.

Phosphorus

< 0.7

< 10.0

< 10.0

0.64

< 0.50

< 0.50

< 10.0

Potassium

< 20

.

.

17.2

4.8

8.7

.

Selenium3

< 0.01-0.05

< 0.050

< 0.050

< 0.50

< 0.50

< 0.50

< 0.050

Sodium

< 150-800

69.41

47.23

470.1

16.00

628.8

2844

Sulfur

< 500

< 250.0

< 250.0

253.0

78.4

271.2

2064

Thallium

0.002

< 0.002

< 0.002

< 0.50

< 0.50

< 0.50

< 0.002

Zinc

< 5.0-25

< 5.0

< 5.0

0.086

0.29

0.091

< 5.0

1Mineral results are reported as mg/kg.

2Recommended maximum levels based on water quality- MSU-DCPAH.

3Labrotory sensitivity not adequate to detect differences in water samples.

 

Within herd, cows from each respective treatment were comingled on pasture. Natural service bulls were turned out to all cows 30 d after treatment administration and remained with cows for the duration of the producer defined breeding season. Transrectal ultrasonography or rectal palpation was used to determine the presence of a viable fetus at least 30 d after the end of the breeding season by a herd veterinarian. Calf weaning weights were collected at the time of weaning for the year of administration [year 1; weaning weights of suckling calves (WWS)] to determine if any effects of injectable trace mineral supplementation administered to the cow pre-breeding affected the weight of the calf at her side.

From the time of pregnancy determination and weaning to calving, females were comingled and managed together on common pastures throughout the grazing season and throughout the wintering period. At the time of calving, birth date and calf sex were recorded. In the current study, the start of the calving season was defined as the date that the third calf was born for each producer operation to remove any early born outliers in the calving season. Calves were then categorized into one of three 21-d interval calving groups based their respective date of birth: born in the first 21 d of the calving season (≤ 21), born from d 22 to 42 (22-42), and born after d 42 of the calving season (≥ 42). If a female was determined to be pregnant at the end of the breeding season but failed to calve the calving group was referred to as “no calf”. The following fall season, weaning weights of calves conceived the year of administration were collected for each herd.  These weights allow for the evaluation of whether pre-breeding administration of ITM had effects on calf performance that began pre-breeding, continued through gestation, and were detectable at weaning.

Statistical Analysis

The MIXED procedure of SAS (SAS Inst. Inc., Cary, NC) was used to analyze all continuous data (blood serum mineral concentrations, calf birth date and calf weaning weights) and the GENMOD procedure was used to analyze binomial data (pregnancy rate and calving distribution). In order to evaluate blood serum mineral concentrations, models included: 1) the effect of treatment among herds for each mineral, and 2) the effect of treatment within individual herd. Multiple models were used to analyze pregnancy data including: 1) the effect of treatment and herd and the interaction between treatment and herd, and 2) the effects of BCS, DPP, and categorical BCS and DPP. Data for days postpartum (DPP) and body condition scores (BCS) were categorized to determine differences in groups of data. For DPP, cows were ≤ 60, 61-70, 71-80 or > 80 based on the interval from calving to the bull turnout date. For BCS, categories used were < 4, 4, 5, or > 5 based on their cow condition at the time of treatment administration. For weaning weights, the model included herd and treatment and the interaction between herd and treatment. Lastly, models for mean calving date, and the proportions of cows calving in defined caving periods (≤ 21), 22-42, and ≥ 42) included herd, treatment, and the interaction. Means were separated using the LSMeans procedure of SAS and significance was declared at P < 0.05).

Research results and discussion:

The current study was conducted to evaluate the effects of a single pre-breeding administration of an injectable trace mineral supplement on pregnancy rate and weaning weights in commercial beef herds. The injectable trace mineral supplement is labeled for 2 administrations; one at four weeks before calving and one at four weeks before breeding for beef cows. The treatment in the current experiment was administered at only one of the 2 recommended time points, 30 d before breeding. Prior to treatment administration, free-choice mineral was available for all cows or was included in a total mixed ration (TMR).

Blood Mineral Concentrations

At the time of treatment administration, blood samples were collected on a subset of females. No differences (P = 0.13) were observed in the blood mineral levels between females for Co, Cu, Fe, Mn, Mo, Se, or Zn.

Variation of blood mineral levels did exist among herds for cobalt, copper, molybdenum, selenium, and zinc, whereas no herd differences were observed for iron and manganese (Table 3.). Concentrations of cobalt were greatest (P < 0.01) in herd 3, whereas both herds 3 and 4 had the lowest molybdenum concentrations. While copper levels were all within normal ranges for each herd, greater (P < 0.01) concentrations of copper were observed in herds 1 and 3 which also had the decreased molybdenum levels. Sulfur, copper, and molybdenum interactions have been established in many species. Sulfides have the ability to bind to copper to form insoluble copper sulfide (Suttle, 1991) as well as the ability to interact with molybdenum and form thiomolybdates, or insoluble complexes decreasing absorption (NRC, 2005). Increased molybdenum and sulfur in the diet of a ruminant can decrease the availability of copper and cause a deficiency (Suttle, 1991). High selenium concentrations were observed in each herd, however, in a national geochemical survey done by the U.S. Department of the Interior (2012), soil selenium levels in North Dakota ranged from 0.20 to 0.73 ppm. More specific to various areas of the Northern Great Plains (North Dakota region), a study was completed evaluating selenium concentrations in available forage that represented high, low, moderate, and unknown selenium levels (Pierre, SD, Fargo, ND, Jamestown, ND, and Miles City, MT, respectively; Lawler et al., 2000). Researchers observed a wide variation of available selenium in forage levels (Pierre: 4.07. Fargo: 1.20, Jamestown: 0.50, and Miles City, MT). Furthermore, researchers also evaluated available selenium based on time of year, dates corresponding with early spring growth (June) and high production (July). In Jamestown and Miles City, concentrations of available selenium in forage was less in June than in July (Lawler et al., 2000). While all reported serum levels in the current study are higher than the adequate range (determined by Michigan State University Diagnostic Center for Population and Animal Health) variation does in exist within the state of North Dakota. Lastly, zinc concentrations were all within normal limits for each herd, however herd 1 had the lowest (P < 0.01) concentrations. Although differences were not observed between treatments, as was anticipated relative to the timing of the sample collection, increased herd variation was observed. Herds were located in 4 different counties and all supplemented with varying feed, hay, and mineral supplements.

Table 3.  Mean blood serum levels for each herd

Mineral

Normal Range1

Herd

SEM

P-value

1

2

3

4

Cobalt, ng/mL

> 0.1

0.19a

0.21a

0.79b

0.47a

0.06

0.04

Copper, ug/mL

0.6-0.8

0.61a

0.51b

0.67a

0.57b

0.04

0.03

Iron, ug/dL

110-180

124.50a

148.88ab

158.22ab

162.10b

13.22

0.05

Manganese, ng/mL

1.5-2.5

5.05

2.89

6.17

0.67

1.77

0.08

Molybdenum, ng/mL

4-100

23.32b

31.59c

6.52a

12.44a

2.13

0.05

Selenium, ng/mL

70-100

101.50a

127.00b

107.56a

125.00b

3.49

< 0.01

Zinc, ug/mL

0.9-2.0

0.73a

0.94b

0.93b

0.86b

0.04

0.03

1Normal ranges are based on MSU-DCPA. Levels are determined to be adequate if within listed ranges.

2Mineral levels represented for each herd are averaged values for each herd.

a,b,cMeans differ within herd (P < 0.05).

Pregnancy

Treatment had no effect (P = 0.29) on the proportion of cows became pregnant by the end of the producer-defined breeding season (92.9% and 92.0 for control and ITM, respectively). There was also no treatment effect observed within herd in the proportion of cows that became pregnant within herd (P = 0.27; Figure 1.). Currently, published data on the effects of mineral supplementation on pregnancy rates is highly variable. Pregnancy rates observed in the current study are in agreement with other published studies (Vanegas et al., 2004; Mundell et al., 2012, Arthington et al., 2014), however, are in contrast to others (Mundell et al., 2012; Brasche et al., 2015). When evaluating the effects of mineral supplementation on pregnancy rates to AI, a greater proportion of those females receiving the injectable mineral supplement before calving and before breeding became pregnant to AI (60.2%), compared with to those not receiving injectable supplement (51.2%; Mundell et al., 2012). In contrast, proportions of females pregnant to AI were similar to those administered an injectable trace mineral supplement compared with control females (Vanegas et al., 2004; Brasche, 2015). When evaluating the effects of injectable trace mineral supplementation on season ending pregnancy rates, heifers receiving the injectable trace mineral supplement 30 d prior to breeding had greater season ending pregnancy rates compared to untreated controls, (season ending: 92.7% and 83.3%, respectively; Brasche et al., 2015). This is in contrast to Mundell et al., (2012) in which season ending pregnancy rates were similar for ITM and control treated females. When natural service breeding was the only breeding system used, similar proportions of heifers of reproductive age became pregnant for those administered an injectable trace mineral supplementation 30-d before breeding and control heifers (Arthington et al., 2014). Based on published results, it is important to note the differences in each studies observed results with regard to the time point and breeding system utilized. When natural service breeding was used on commercial beef cattle operations in the current experiment, no advantage was observed for cows injected with a trace mineral injectable supplement.

 

Figure 1. The proportion of cows that became pregnant during the producer defined breeding season. Treatments: CON = control, ITM = injectable trace mineral supplementation. Means differ within herd by treatment (P < 0.05).

Variable effect on pregnancy attainment among studies may be explained by the mineral need of each animal or herd. Each of the above mentioned studies was done using an injectable trace mineral supplement containing copper, manganese, selenium, and zinc. In a study involving free-choice mineral supplementation, Muehlenbein et al. (2001) reported that cows (n = 30 in each group) not supplemented with any type of free-choice copper had greater pregnancy rates in the first 30 d of the breeding season compared to those that were supplemented with free-choice inorganic mineral (86% and 57%, respectively) with organically supplemented cows being an intermediate (75 percent). The following year, a replicate study was completed with the same cow groups and treatments. After year two of the study, cows that were supplemented with organically bound copper had greater pregnancy rates in the first 30 d of the breeding season, when compared to those not supplemented with organically bound copper (85% and 61%, respectively), with inorganic mineral supplemented cows being an intermediate (80%; Muehlenbein et al., 2001). Differences in years were thought to be caused by copper status at the beginning of the treatment period, as year 2 liver concentrations of copper were reduced compared with year 1. Researchers hypothesized that the supplementation in the second year was more beneficial, potentially due to levels in year 1 being much lower (40 mg/kg and 58 mg/kg, respectively).

Weaning Weights

Weaning weights of suckling calves were recorded to determine if the injectable trace mineral supplement may have had an effect on nutrition of the dam and, therefore, the weight of the calf at her side. Weights of calves from ITM dams were not different (P = 0.90) than of calves born from CON dams (283.1 ± 2.0 kg and 287.0 ± 2.1 kg, respectively). Weigths were also not different within herd between the CON and ITM treatments (P = 0.32). The nutritional status and therefore body condition of a cow both at calving and postcalving are associated with milk production (Roche et al., 2009). Optimal BCS or the ability of a females to be in a positive energy balance may positively affect the milk produced and therefore the weight of the nursing calf (Roche et al., 2009). In contrast to the current study in which calf weights were collected, Mundell et al. (2012) observed no effect of trace mineral supplement on cow body weight and body condition 30 d before calving until weaning. In contrast, supplementing cows with high levels of inorganic mineral resulted in greater BW loss from March 13th to May 13th (the time after calving to before breeding) compared with supplementing high levels of organic mineral or low levels of inorganic minerals (Stanton, et al., 2000). It is important to understand the differences in supplementation of ITM at a single time period versus a fed mineral supplemented for roughly two months.

Figure 2. The effect of ITM supplementation on calf weaning weights. Treatments: CON = control, ITM = injectable trace mineral supplementation. Means differ within herd by treatment (P < 0.05).

Calving Distribution

            At parturition, calf birth date and sex were recorded. Mean calving date was not different (P = 0.45; Figure 3.) for calves born from dams administered the injectable trace mineral supplementation, compared with calves born from CON dams (25.7 ± 0.75 d and 24.6 ± 0.72 d, respectively). In addition, no difference (P = 0.53) was observed in the distribution of calving when the calving season was divided into 21-d increments (Figure 4.).

Figure 3. The mean date of birth in the calving season for each herd. Treatments: CON = control, ITM = injectable trace mineral supplementation. Means differ within herd by treatment (P < 0.05).

 

Figure 4. The proportion of cows calved by 21-d increments of the calving season between trace mineral treatments. Treatments: CON = control, ITM = injectable trace mineral supplementation. Means differ within herd by treatment (P < 0.05).

In contrast to the current study, the proportion of calves born in the first 20 d of the calving season was greater for cows supplemented with an injectable trace mineral supplement 30 d before calving and 30 d before breeding compared with control or unsupplemented cows (60.2% and 51.2%, respectively; Mundell et al., 2012). In the current study, natural service breeding was used whereas in Mundell et al., (2012), artificial insemination was utilized. A benefit of breeding with artificial insemination is an increase in the proportion of cows calving early in the calving season (Rodgers et al., 2012; Steichen et al., 2013; Crosswhite et al., 2016). It is unclear if the trace mineral injectable supplement in the study by Mundell et al., (2012) caused an increase in the proportion of calves born earlier in the breeding season when compared to controls. When evaluating differences in results, it is important to recall that natural service breeding was using in the current study as well as only administering one of the recommended doses of ITM.

Survey questions are in the process of being created for distribution to cooperating producers.

Conclusions

The incorporation of an injectable trace mineral supplement administered 30 d before bull turnout did not affect the proportion of cows that became pregnant in the breeding season on commercial operations, calf weaning weights, or the distribution of calving.

It is important to note that only a single pre-breeding injection of the trace mineral product was administered compared with the label recommendation or two doses; one pre-calving and one pre-breeding.

Participation Summary
5 Farmers participating in research

Educational & Outreach Activities

1 Journal articles
1 Published press articles, newsletters
1 Webinars / talks / presentations

Project Outcomes

Project outcomes:

Accomplishments

To date, treatments have been applied at 5 operations in North Dakota. At each operation, blood, feed, and water samples have been collected. Similarly, objectives 2 and 3 are not yet completed as an extension bulletin is being created based on baseline mineral levels as well as survey data based on producer involvement. The survey has been completed and researchers are awaiting producer responses.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.