I mentioned that I learned some other interesting things from my forage lab results from last fall. In the past, I’d just lumped all the samples together, in a rough attempt to represent the ratio of grass, clover, and other broadleaf plants we have in all three of our fields. But I feel that I have been getting less lamb growth on our Reed Canarygrass (RCG) field. So I wanted to test that separately this time, to see if I could explain the difference. RCG has a good reputation for being high protein, so it seems odd that my sheep don’t seem to perform as well on it. They are also  more prone to diarrhea while in that pasture.

Our RCG field is pretty much a monoculture. There are a couple of spots of buttercup and a bull thistle here and there, but hardly anything else can compete or cohabitate with RCG. Our other field is a more traditional cultivated pasture with several varieties of pasture grass; plus white clover, buttercup, and dandelion. I did include some of those broadleaf plants in with the grass, doing my best to represent the ratio in the field in the sample ratio.

Below is a comparison table between the two fields, along with notes I have about each metric. The numbers in bold are areas of interest where the two fields differed.

Sample/Year

2011
Field 1

2011 RCG

Notes

%Moisture

67.80%

60.50%

Calculated out for the rest of the values

CP

25.4

29.7

8% adequate for dry ewes, 12-14% for growing lambs, 16% ideal for post-weaning age group

ADF

21.50%

21.10%

Acid Detergent Fiber

NDF

34.90%

36.40%

Neutral Detergent Fiber

RFV

192

185

Relative Feed Value 100 = alfalfa in full bloom (late stage, early stage alfalfa is higher)

TDN

75.6

76.1

60+ is good, 55 adequate for dry ewes, 70 good for growing lambs, 72-74 for post-weaned lambs

DP

21.00%

25.30%

Digestible protein

DDM

72.1

72.5

Digestible dry matter

DMI

3.4

3.3

Dry matter intake

DE

3.33

3.35

Digestible energy

ME

2.92

2.94

Metabolizable energy

NEL

1.74

1.75

Net Energy Lactation

NEM

2.3

2.32

Net Energy Maintenance

NEG

1.6

1.62

Net Energy Gain

Sulfur

0.37%

0.42%

0.1% recommended, 0.4% max; interferes w/ copper, Se, and thiamine absorption

Phosphorous

0.53%

0.47%

0.3% recommended

Potassium (K )

3.60%

3.52%

0.65% recommended, 3.0% max; hi levels can block magnesium, risking grass tetany. Depresses Ca, Mg and Boron uptake.

Calcium

0.44%

0.45%

.4%+ adequate

Magnesium

0.27%

0.26%

0.1 recommended, 0.4% max. Nutritionist recommends supplementing with this, to offset high K.

Zinc

37 mg/kg

56 mg/kg

10+ adequate; high zinc depresses copper

Manganese

74mg/kg

156 mg/kg

40+ adequate, 1K max

Copper

11 mg/kg

10 mg/kg

7+ adequate, 115 max; 14-20 recommended for sheep w/ high Mo

Iron

578 mg/kg

133 mg/kg

levels above 400 cause copper tie-up; 50 recommended, 1K max; also binds with zinc,potass, & vit E

Molybdenum

not tested

not tested

Ideal below 1, above 3 causes copper tie-up, 6 max. Tested in 2009, was 4ppm.

Ca:Phos Ratio

0.83

0.96

1.3:1 – 1.5:1 is ideal, 2:1 or 3:1 may be OK- too high reduces phos absorption, causes bone problems. Urinary calculi from reverse: too much phos.

Cu:Mo Ratio

2.75

2.5

Ratio below 4:1 causes copper tie-up (using 2009 value for Mo)

N:S Ratio

10.98

11.31

Desirable below 10:1, according to this link

Ca:Mg Ratio

1.63

1.73

Desirable 2:1

Ca:K Ratio

0.12

0.13

Ideal 1:1

Se

1.25 mg/kg

1.39 mg/kg

<0.1ppm is deficient, >2ppm is toxic.

Crude Protein

The RCG is higher protein, at a whopping 29.7%. From my notes from the Woody Lane lecture in 2009, here’s how it stacks up with other common feedstuffs:

image

Relative Feed Value

The Relative Feed Value (RFV) is a little lower, and the Neutral Detergent Fiber (NDF) is a little higher than the traditional pasture. RVF is an inverse function of NDF and ADF (Acid Detergent Fiber), an reflects an estimate of both intake and digestibility. Since the NDF tells us the RCG grass is a little more “bulky,” it’ll fill the sheep up a little quicker than the regular grass, and render less calorie intake.

And the other number that plays into this is %moisture. This is calculated on the grass samples when they arrive in the lab, but then it’s equated out of the rest of the values (all the rest of the numbers are calculated as 100% dry matter). The traditional grass sample had more water than the RCG; so even though the RCG has more bulk, it’s probably true that if a sheep eats three pounds of either grass and gets full, it’ll get about the same TDN.

Total Digestible Nutrients

imageTDN is the main score used to calculate rations, and is awesome on both samples. Well into the range of feed which is good for growing meat lambs.

Minerals

As for minerals, here are what I think are interesting differences in the RCG.

GrassHigher in sulfur

Both pastures are on the high end, and earlier in the year I had additional sulfur in the supplement. I am going to back off on this. Though sulfur tangles with copper and thiamine, this isn’t my main concern.

Lower in phosphorus

Both fields have an imperfect calcium: phosphorous ratio, the phos is too high. It’s less of a problem in the RCG field. I have gone back and forth with mixing in dolomite into their supplement (this is calcium magnesium carbonate); and am returning to it to help bring up the calcium. This is mainly a concern for male sheep, as when this ratio slips (which is exacerbated by grain feeding) it can cause urinary calculi.

Higher in zinc

Yay, this is good, and both fields are plentiful in zinc; though oddly my sheep livers are testing too low in it, still. Zinc is really important for hoof health. I had really high zinc in my supplements all year, so there must be something going wrong with its binding with copper and iron.

Much higher in manganese

Our fields are higher than needed, but not even close to an excessive amount; and the sheep livers test high-normal. So it’s not that interesting in itself, other than to note that it also hinders iron absorption. I am backing off on this in the supplement just due to that. Bridge

Much lower in iron

Both fields are in the ok range for amount of iron, and I was feeding piles if iron in my supplements all year. Yet, my sheep are still too low in iron. I’ve seen a few cases of bottle jaw which I do not think were caused by parasites. So something is awry here. I suspect that the RCG field is telling me that once the sheep drop below a certain level of iron intake, it’s limiting their growth. Since the iron is there, I need to back off on the things that interfere with it: namely copper and manganese.

Higher in selenium

I talked about this in a prior blog post, that I was surprised to find out that we have plenty of selenium, and I was probably bordering on excess given the supplements I was using. So, this could be another area where this field was just tipping the balance a little too much and curtailing growth.

Next Iteration

So there’s my assignment for this year: keep zinc and iron as high as possible, lower copper, manganese, sulfur, and selenium, increase calcium. I believe I can achieve this by mixing the Cattlemen’s supplement with dolomite and one of American Stockman’s mixtures, or Morton’s IOFixt.

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