Tag Archives: small ruminants

Pasture Weeds as Mineral Sources for Goats

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The following article was originally published in the November 2013 newsletter from Hoegger Goat Supply (Hoegger Farmyard).

Introduction

There have been several blog articles published recently at Hoegger Farmyard that deal with the problem of copper (Cu) deficiencies in goats. As mentioned, this deficiency can be either primary, or secondary. The former is due to low Cu content of forage whereas the latter reflects the interaction between Cu and other chemical elements (minerals), such as iron (Fe), molybdenum (Mo) and sulfur (S). For these reasons, goats are usually fed Cu supplements to avoid a number of symptoms ranging from loss of pigmentation in hair coat to life-threatening anemia.

Copper deficiency is more pronounced in some regions than others and depends, in part, on the chemical composition of soil and underlying rocks. For example, on our farm in the karst limestone region of southern Indiana (Mitchell Plain), Cu concentrations in grass hay (~8 ppm) and commercial feed (~25 ppm) are adequate to meet the nutritional requirements of our dairy goats (ppm = parts per million, refer to Table 2). In contrast, high Cu supplementation (~1500 ppm Cu bolus) is required in the Adirondack Mountains (upper New York State) where thin, nutrient-poor soils have formed from glacial debris (tills) (refer to blog article by Rose Bartiss on copper deficiency in goats at Hoegger Farmyard).

In nutrient-poor soils, the roots of pasture plants, such as grasses and weeds, have some ability to selectively absorb and concentrate essential minerals. One interesting example from crop science is ragweed, which can have Zn concentrations seven times greater than those of corn leaves at tassel! In other words, as most gardeners know, weeds can deplete soils of nutrients. Goats are great “weedeaters”, so why not use organized plots of certain pasture weeds to supplement minerals in their diet? The trick is to find the right weeds. You want the nutritive value but you don’t want to propagate a host of noxious weeds that will upset your neighbors and the local extension agent.

Our pastures consist of a variety of weeds, including chicory, dandelion, broadleaf dock, common lambsquarters, common and giant ragweed, narrow-leaved (buckhorn) plantain, bull thistle, redroot pigweed, Sericea lespedeza and Jerusalem artichoke (http://oak.ppws.vt.edu/weedindex.htm). We have seen our goats browse all of these weeds until heavy frost near the end of October. We decided to determine macronutrients and micronutrients for some of the more palatable (and controllable) weeds and see if we could find several good candidates for our pasture plots. Let’s face it, goats are browsers and were not meant to graze grass pastures. Their feeding habits and nutritional requirements are more similar to deer than to other domestic ruminants.

Background

The idea to use weeds as alternative pasture plants is not new.  Harrington et al. (2006) (http://www.nzpps.org/journal/59/nzpp_592610.pdf) briefly reviewed the pertinent literature and determined the mineral composition of several of the weeds noted above. The weeds were sampled from both conventional and organic plots on the Tokomaru silt loam (soil texture with high proportion of silt to sand and clay) within the Dairy Cattle Research Unit of Massey University, Palmerston North, New Zealand. Both plots were fertilized within the last 12 months (refer to Harrington et al. for more details). Results indicated that common weeds have elevated concentrations of several different nutrients relative to conventional pasture forage, such as perennial ryegrass and white clover.

Methodology

The weeds in our study were collected in the same pasture areas as those browsed by goats. Pasture soils are predominantly silt loams (Crider series), which developed from weathered limestone (calcium carbonate) and loess (windblown sediment). Only the upper ~15 cm (6 in) of each plant was included in the samples (~100 g = 0.22 lb), mimicking as closely as possible the feeding habits of our goats.  At this time of year (August-September), some of the weeds had very fibrous stalks with seed heads, e.g., ragweed, lambsquarters and pigweed. With the exception of chicory, only one sample of each weed was collected (no replicates). Chicory was sampled twice to evaluate the nutrient distribution between basal leaf rosette (vegetative state) and flowering stalk (reproduction stage). Hay samples consisted of cores taken from 12-20 representative bales. No fertilizers other than composted horse manure were applied to pastures (www.mitchellplainfarm.com/on-farm-manure-and-mortality-composting.html). Samples were analyzed by the Dairy One Forage Laboratory, Ithaca, New York, using inductively coupled plasma mass spectrometry (ICP-MS).

Results and Discussion

Some of the results from Harrington et al. (2006) and our new analyses of weed and hay samples are compared below in Tables 1 and 2.  Note that the unusually high Na concentrations in the New Zealand data are due to atmospheric deposition of sea salt.  Several of the weeds analyzed in this study are enriched in both macronutrients and micronutrients relative to grass and legume hays, consistent with the study by Harrington et al. (2006). For example, Ca in ragweed and Jerusalem artichoke is ~50% higher than that in alfalfa–rich hay (Table 1). Zinc, the most deficient micronutrient next to Cu, is enriched in all weeds with the exception of Sericea lespedeza and redroot pigweed (Table 2). The highest Cu concentrations are found in ragweed, chicory and Jerusalem artichoke. These weeds are also good sources of P, Mg and K.

Pigweed, which is a very popular browse among our goats, has about two times the P and Mg content as alfalfa-rich hay. However, pigweed has the potential to accumulate high nitrate (NO3–) concentrations during extreme environmental conditions, such as drought. After ingestion, nitrate is converted to nitrite (NO2-), which interferes with hemoglobin’s ability to carry oxygen to tissues. The nitrate concentration measured for pigweed in this study was ~0.25% (2500 ppm), which is below the maximum level recommended for cattle (<0.6%) (Radostits et al., Veterinary Medicine, 9th ed., 2000). Relatively high nitrate concentrations can also occur in lambsquarters, a nutritious source of Mg, K and Mn. Because goats are browsers and there is a large diversity of weeds in our pastures, they don’t spend much time feeding on one plant. As a result, they can avoid potential toxic effects and still make use of nutrients in both pigweed and lambsquarters.

Sericea lespedeza is high-tannin forage that has been shown to be effective in controlling internal parasites in goats (http://www.scsrpc.org/SCSRPC/Files/sericea_lespedeza.pdf). It’s not a favorite of our goats but they will browse the tops when confined to pastures dominated by this weed. Lespedeza is a legume and, with the exception of Fe, has a nutrient profile very similar to the alfalfa-rich hay in Tables 1 and 2.

Keep in mind that the concentrations of plant nutrients do not necessarily reflect the actual amount absorbed by goats because of antagonistic effects, i.e., the negative effect of one mineral on another. For example, Mo and S can form insoluble compounds with dietary Cu in the rumen that “lock up” Cu and limit its absorption (www.dairygoatjournal.com/87-3/coppers_role_in_goat_health/).

Finally, let’s determine what weeds are best suited for our pasture plots. Ragweed is chock-full of nutrients but it is not a plant you want to propagate in your pasture. The alternative is to temporarily fence goats in ragweed areas, a common practice by goat owners. A similar strategy can be used for pigweed and lambsquarters.  Sericea lespedeza is prolific in this area and is the major goat forage in one of our pastures.

The best choices for cultivation based on our study and the results of Harrington et al. (2006) are dandelion, chicory, narrow-leaved plantain and Jerusalem artichoke, all of which are good sources of Cu and Zn. Cu and Zn concentrations in chicory are highest when the plant is grazed in the vegetative state during leaf growth stage (Table 2). Although the leaves were sampled for analysis, tubers of Jerusalem artichoke are particularly tasty to animals (and humans) and enriched in vitamins and minerals. If you are going to expend all of this effort, why not plant weeds that are good for both you and your goats!

It is important to remember that this is a preliminary study. A more systematic, scientific approach with replicate samples would be needed to fully evaluate the use of weeds as nutritional supplements for goats. The nutrient concentrations in Tables 1 and 2 are specific to our local area and will vary depending on soil type, pasture fertilization and maturity stage of the weeds sampled.

Table 1. Macronutrients (% dry matter) in hays and weeds from Harrington et al. (2006) and samples collected near Central, Indiana. Values highlighted in bold are significantly higher than perennial ryegrass or white clover (statistical analyses by Harrington et al.).

Hay and Weed Samples from Harrington et al. (2006)

                        %

 Ca

  P

 Mg

  K

  Na

   S 

Perennial ryegrass

0.42

0.37

0.173

3.80

0.182

0.347

White Clover

1.19

0.347

0.237

2.83

0.205

0.213

Chicory

1.18

0.663

0.393

3.80

0.591

0.627

Narrow-leaved plantain

1.77

0.480

0.253

1.97

0.618

0.530

Broad-leaved dock

0.80

0.430

0.520

4.10

0.026

0.287

Californian thistle

1.87

0.357

0.307

2.93

0.047

0.570

Dandelion

0.96

0.570

0.353

3.43

0.420

0.393

 Hay and Weed Samples Collected near Central, Indiana

                        %

 Ca

  P

 Mg

  K

 Na

  S 

Gamagrass

0.41

0.26

0.20

1.37

0.016

0.18

Alfalfa (70%)/orchard grass

1.38

0.21

0.31

1.58

0.009

n/a

Ragweed (Giant)

2.14

0.40

0.40

3.59

0.004

0.52

Lambsquarters

1.28

0.30

0.50

6.60

<0.001

0.37

Chicory (flower stalks)

1.28

0.38

0.26

2.08

0.020

0.31

Chicory (basal leaf rosette)

1.49

0.55

0.32

4.65

<0.001

0.66

Narrow-leaved plantain

1.86

0.29

0.25

3.26

0.003

0.45

Sericea lespedeza

1.31

0.21

0.18

1.31

<0.001

0.19

Jerusalem artichoke (leaves)

2.20

0.38

0.43

3.37

<0.001

0.32

Redroot pigweed

1.28

0.49

0.63

3.22

0.002

0.24

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Note: To convert % to mass multiply by 10, e.g., gamagrass contains 0.41 % Ca = 4.1 g/kg Ca = 4.1 g/2.2 lbs Ca (3 kg hay = 6.6 lbs = 12.3 g Ca). Interpretation of chemical symbols: Ca (calcium), P (Phosphorous), Mg (Magnesium), K (Potassium), Na (Sodium), S (sulfur); n/a (not analyzed).

Table 2. Micronutrients (% dry matter) in hays and weeds from Harrington et al. (2006) and samples collected near Central, Indiana. Values highlighted in bold are significantly higher than perennial ryegrass or white clover (statistical analyses by Harrington et al.).

Hay and Weed Samples from Harrington et al. (2006)

          ppm = mg/kg

 Fe

Cu

 Zn

Mn

 Mo

Perennial ryegrass

151

7.9

22.0

 99

0.64

White clover

109

8.6

22.0

 55

0.22

Chicory

167

18.6

57.7

161

0.42

Narrow-leaved plantain

182

15.1

37.7

109

0.27

Broad-leaved dock

  95

  7.6

30.7

283

0.42

Californian thistle

139

17.0

41.7

120

0.21

Dandelion

115

14.2

37.0

  93

0.373

 Hay and Weed Samples Collected near Central, Indiana

          ppm = mg/kg

 Fe

Cu

 Zn

 Mn

 Mo

Gamagrass

239

  8

  25

  57

 1.6

Alfalfa (70%)/orchard grass

218

10

  20

  70

 0.7

Ragweed (Giant)

144

16

  72

  79

 0.5

Lambsquarters

  75

  5

  32

204

 0.4

Chicory (flower stalks)

  90

12

  41

  24

 0.8

Chicory (basal leaf rosette)

117

18

  72

  36

 0.8

Narrow-leaved plantain

106

13

  46

  38

 0.6

Sericea lespedeza

  98

10

  27

  65

 0.8

Jerusalem artichoke (leaves)

252

27

104

  79

 0.6

Redroot pigweed

132

  6

  28

  46

 2.1

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Note: ppm = parts per million where 1 ppm = 1 mg/kg, or 1 mg/2.2 lbs, e.g., 3 kg (6.6 lbs) gamagrass contains 8 mg Cu/2.2 x 6.6 = 24 ppm Cu. Interpretation of chemical symbols: Fe (Iron), Cu (Copper), Zn (Zinc), Mn (Manganese), Mo (Molybdenum).

 

Blood-Sucking Creatures in Your Goat’s Stomach!

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I’m back with everybody’s favorite topic – worms, of course! I would put away that food you are munching on until you have finished reading this blog!

I want to share with you results from a simple comparative study that I carried out on common goat dewormers. It’s very unscientific but I thought it might be useful to some goat owners. As I mentioned in my previous goat blog, worms (parasites) are the number one problem affecting meat and dairy production worldwide, particularly in the Southern Hemisphere and Third World countries. It’s a major problem because goat worms are becoming resistant to all major groups of chemical dewormers (Kaplan 2013) The one parasite that’s the most serious threat is a guy called Haemonchus contortus, also known as the barber pole worm, or the blood worm. It makes a living sucking blood from the lining of your goat’s stomach and can cause severe anemia and, ultimately death, if not controlled.

Here’s an image of the culprit and some of its eggs captured with a fluorescence microscope. Ultraviolet (UV) light  is causing the worm and eggs to “fluoresce”, or emit light in the visible portion of the spectrum.  To give you an idea of scale, the long dimension of the eggs is about 100 micrometers, or 0.1 mm. This is a very ingenious application of the property of fluorescence to an important veterinary problem. I am sure that many of you have seen fluorescent mineral displays in geology departments and museums. It’s the same principle. Unlike some minerals, however, Haemonchus eggs are not naturally fluorescent. Therefore, the key is to find a chemical substance that (1) binds only to Haemonchus eggs in the fecal sample, and (2) fluoresces in UV light. In this case, the eggs are coated or “stained” with a plant protein (lectin) called peanut agglutinin. You can read a press release about the development and application of this technique at http://www.vet.uga.edu/pr/sheep-parasite.php.

Haemonchus contortus with several of its eggs as viewed with a fluorescence microscope. Photo credit: © 2009 The University of Georgia College of Veterinary Medicine.

Haemonchus is an example of a strongyle worm (small roundworm) found primarily in hotter, more humid climates. Unfortunately, its eggs cannot be distinguished from those of other species in this group based on size, or morphology (shape). The fluorescent staining method is a breakthrough in goat and sheep parasitology because it will now be possible to rapidly and inexpensively detect the presence of Haemonchus eggs and take the necessary steps to control this pathogenic organism (one worm can lay up to 10,000 eggs per day!).

I have set up my own small parasitology lab at our farm. It’s easy to do, relatively inexpensive and avoids the high cost of fecal tests, currently about $50.00 per test (quantitative analysis) at veterinary clinics in our area. I also determine my own egg counts for my mustang horses. It’s easy to learn to identify the most common parasites. For example, web sites such as the Maryland Small Ruminant Page, provide a number of general parasitology links with images and tutorials.

This is a photo of my lab for determining fecal egg counts using the McMaster technique. Other than a microscope, you will need a standardized fecal solution (in this case, sodium nitrate, or Fecasol, Specific Gravity =1.20) for floating the eggs, McMaster slides, gram scale (optional), an assortment of glassware, a strainer and funnel, and some exam gloves. I use the Modified McMaster Technique described by Ray Kaplan DVM, PhD and James Miller DVM, PhD in the article Modified McMaster Egg Counting for Quantitation of Nematode Eggs. I changed their procedure slightly by including a step to filter out the solid fraction in the fecal solution. This makes it easier to extract the liquid fraction and load the McMaster slide. When interpreting the results of the McMaster technique, it is important to remember that egg counts might not reflect the actual number of worms present. Refer to The RVC/FAO Guide to Veterinary Diagnostic Parasitology for a list of the factors that can affect egg counts. This web site is also a good source for other information about fecal analyses of small ruminants.

The objective of my experiments was to determine the dosage of chemical dewormers necessary to reduce the population of internal parasites by at least 90-95% after 2 weeks. This is referred to as the fecal egg count reduction test (FECRT) in the scientific literature. There are number of different types of parasites in goats but only those eggs belonging to the strongyle group were counted. These are the most common eggs observed in fecal analyses of goats.

The current recommendation by parasitologists is to use one dewormer until FECRT < 95%, indicating significant parasite resistance (S. Mobini, DVM, Fort Valley State University, pers. comm.). In practice, the actual FECRT% considered acceptable in parasite control programs will depend on a number of factors, including the availability of dewormers with higher efficacy (If a drug has high efficacy, 0% of worms will survive the dewormer). However, as FECRT results approach 80%, parasite resistance and associated health effects will begin to increase more rapidly. For example, in sheep FECRT < 80% has a negative effect on lamb growth rate.

Included in this study were Rumatel® (Morantel Tartrate), Panacur®/Safeguard® horse paste, Moxidectin horse paste (Quest® Gel) and liquid (injectable CYDECTIN®), Ivermectin (horse paste) and Dectomax® (injectable). For the time being, I did not consider Levamisole (Levasole, Tramisol and Prohibit® Drench), or some of the other benzimidazoles, e.g., Valbazen, which is unsafe for pregnant animals in first trimester. Because of the small number of animals in my herd (normally four), I have not used the oral drenches, or suspensions, recommended for goats, which are more bioavailable than horse pastes. Oral drenches, such as IVOMEC® sheep drench (goat dosage = 6 ml per 25 lbs body weight), are usually sold in 1-liter (1000 ml) containers with a 1-year expiration date.

I normally don’t deworm until the level of anemia is equal to, or greater than, “3” based on the FAMACHA system (“5” being severely anemic). The FAMACHA test compares the color of the lower eyelid to a color chart to determine the level of anemia from Haemonchus infection. If you are not familiar with FAMACHA, or parasite control in general, you can read about it at the web site for the American Consortium for Small Ruminant Parasite Control (ACSRPC).

Summary of results from comparative study using McMaster egg counting technique

Rumatel® (Morantel Tartrate): Only dewormer approved by FDA as an additive to goat feed. Advantage is that there is no withdrawal period for milk. Recommended dosage on bag is 2 lbs. In fact, it takes 2 lbs daily for two successive days to achieve FECRT > 95% after 2 weeks.  Good alternative if you are already feeding processed food or milking your goats. I recently switched to Goat Care-2X medicated pellets (generic Rumatel® 88). Same stuff but more concentrated so one treatment (4 oz per 50 lbs body weight = 88 gm Morantel Tartrate per 100 lbs) will produce similar results for FECRT.

Panacur® (horse paste): One dose at 2-3 X body weight is ineffective (well known from goat literature). Three successive daily doses at 2-3 X body weight will reduce FECs by > 90% after 2 weeks (for any horse owners out there, this is the Panacur Powerpack for goats!). Panacur® and Safeguard® are the same drugs sold under a different label (Fenbendazole). The recommended goat dewormer is Safeguard®/Panacur® suspension (see ACSRPC table of anthelmintic dosage and withdrawal times below).

Moxidectin (Quest® Gel horse paste)  versus liquid (injectable CYDECTIN®): FECRT for both dewormers was > 90% after 2 weeks. Dosage for paste is 2 X body weight, that for liquid only 1 X, as recommended by ACSRPC. Downside to using the injectable liquid is cost for a small herd — about $110.00 for 200 ml. Philosophy behind using the liquid is that less is required (it has a longer residence time, or persistence, in the animal’s system) so parasite drug resistance will develop more slowly. As it turns out, the injectable form of Moxidectin (CYDECTIN®) is no longer recommended for use by the ACSRPC because of its greater withdrawal times (120-130 days) for consumption of meat. In addition, a recent study indicates that Moxidectin has a higher efficacy when administered orally in cattle (CYDECTIN® Drench) rather than injected subcutaneously, or applied topically (pour-on). Oral use of pour-on CYDECTIN® is not recommended for goats.

Ivermectin (horse paste) and Dectomax® (injectable) (avermectin group): Not effective in significantly reducing FECs for my small herd (FECRT << 80%). Neither the Ivermectin (IVOMEC®) sheep drench, or injectable ivermectin (IVOMEC®), administered orally or subcutaneously, were used in this limited study. Both routes of injectable ivermectin are considered (extremely) extralabel because the IVOMEC sheep drench is available.  In addition, the formulation (solution of chemical substances plus active drug) for the oral drench is more bioavailable than ivermectin injectable given orally (Patty Scharko, DVM, Clemson University, pers. comm.). For those of you with lactating dairy goats, note that ivermectin injectable has a 40-day withdrawal time for milk (FARAD Digest 2000).

For reference, anthelmintic dosage and withdrawal times for goats are given on the ACSRPC web site. Note that Rumatel® 88 listed in the footnote to ACSRPC table has 0 days milk withdrawal time for 88 gm/100 lbs body weight dose (refer to withdrawal charts in Compendium of Veterinary Products 2014).

A few concluding remarks about the drug class of macrocyclic lactones (MLs), which includes two closely related chemical groups – the avermectins and milbemycins. Ivermectin and Doramectin (“Dectomax®”) are avermectins whereas Moxidectin is a member of the milbemycin group. Ivermectin and Moxidectin have a longer persistence in the body, which means that these dewormers can persist in lethal concentrations for an extended period of time. Relative to Ivermectin, Moxidectin provides a greater persistent period and a greater efficacy against resistant worms.

Keep in mind that Ivermectin has been used extensively in goats since the 1980s so one might expect a greater parasite resistance to this drug. Moxidectin is a more potent drug and the last of the MLs to be introduced. Therefore, parasite drug resistance should develop more slowly. Unfortunately, Moxidectin is no longer effective in controlling parasites in many sheep and goat farms in the eastern and southern U.S. (Kaplan 2013). This trend will continue if we don’t make judicious use of dewormers, and employ effective pasture management practices that disrupt the life cycle of parasites.

So far we have only talked about chemical dewormers. There are other alternatives such as herbal remedies and pasture plants but how effective are they in controlling internal parasites? More on this topic at the ACSRPC web site.

At present, we are trialing the herbal product Verm-X (certified organic, available from ebay) and pasturing our goats in areas where the tannin-rich plant Sericea lespedeza is particularly abundant. For a nutrient profile (major and trace minerals) of Sericea lespedeza (a legume) link to my blog article on Pasture Weeds as Mineral Sources for Goats.

Author (George Lager) with his prized milking goat Fanny.

Author (George Lager) with his Alpine goat Fanny.

As a disclaimer, I need to mention that I am not a veterinarian and cannot provide medical advice for your goats. All the information presented here is based on work with my dairy goats, the ACSRPC web site and what I have read in the scientific literature. Updated July 17, 2014