Grazing Corn Plants as an Alternative Summer Annual Forage for Growing Lambs to Reduce Chemical Dependency and Parasite Resistance to Chemicals

Two acre plots of Channel Seed brand corn were planted on May 10th, 30th, June 19th,and July 4th. Soil tests were taken and appropriate amounts of phosphorus, potassium and nitrogen were applied at planting. Nitrogen was added at the 4 leaf stage to plots 1 and 2.

Nitrogen was not added to plots 3 and 4 due to extreme dry weather and fear of nitrate poisoning was present. Corn was planted under no-till and good weed control was achieved. It was planted on 30 inch rows at a population of 32000 seeds per acre and had an approximate 30000 plant population. This was chosen over a 15 inch width row to allow mechanical harvesting of excess corn, although 15 inch rows would work for grazing. Due to extreme dry weather plot 4 planted in July was a failure. Plot 3 suffered apparent production loss as well while plots 1 and 2 received enough rainfall early in the season to produce well although weather probably impacted all plots to some extent.

Lambs were born in April then rotationally grazed on grass legume mixed pastures with 3 day rotations through weaning alongside their mothers. Composite FEC (fecal egg counts) were used to monitor lambs prior to weaning. Lambs were weaned in early July with FECRT (fecal egg count reduction test) done between 7/3 and 7/18 to assure chemical dewormers were working effectively. Lambs were weighed 7/3 and 7/18 and then again on Sept 7th. Birth dates were recorded to measure weights at days of age. Birth weights were not available so a 10 lb. birth weight was assigned to each lamb.

Lambs started grazing corn on July 3rd. Lambs appeared to have no issues with acclimating to the new forage with intake being reasonable when measured with body weight on a DM (dry matter) basis. Lambs would eat the low leaves first then shoulder the upper plant over for them to be able to reach the upper half. The lambs consumed all the leaves and the upper half of the stalk and ear if present. On July 18th data was collected to measure fecal egg count, weight also, allowing close inspections of lambs for health issues. It was noted at that time that a high percentage of the lambs were showing signs of sore mouth. It is felt that the sore mouth infection in the lambs contributed to the weight gain during this time period being low at only .10th of a pound per head per day but we were unable to say for sure. The lambs remained clean from parasitism through the duration of the project due to starting the lambs clean from parasites then grazing a parasite free field of corn. Temporary netting was used only allowing lambs access to enough corn for three days for a couple reasons. One to improve utilization of the forage the second was to keep lambs from ingesting new larva deposited by the grazing lambs. It is known that it takes 3-4 days at the least in ideal conditions for a Haemonchus Contotrus (blood sucking intestinal parasite) to develop from an egg shed in the fecal matter of sheep into a L3 infectious larva. A back fence was used to keep lambs from grazing in areas where they previously grazed. Lamb weights at the start of the project was 43.7 lb. average with only .10 of a pound per day gain for the first data period with an ending weight of 45.2. There were a couple thoughts on that at the time as to why the low gain. One was the effects of sore mouth as well as stress from weaning. Weights improved throughout the project with an average daily gain of .38 lbs per head per day from July 18th to Sept 7th with four lambs gaining .5 lbs per day. The goal of removing the need to use chemical dewormers was achieved as suspected by taking parasite-free lambs to the corn fields and rotating them on three day rotations with a back fence. The only time these lambs received dewormer was at the start of the corn grazing on July 3rd.

Five different sets of forage quality and quantity test were done. Forage quality tests were done by Dairy One forage testing lab in New York. Quantity tests were done by taking a plant population count and then taking an average green weight of 10 plants. To figure a DM weight on the plot the forage tests were used to figure % of moisture or % of DM. Plant utilization was figured by weighing the remaining amount of the corn plants after grazing. The corn was fairly predictable on growth with all plots being ready to graze about 45 days after planting. Crude protein was highest just prior to the plant developing a tassle. After the tassle developed the CP dropped fairly quick as one would expect, that being said with the ear developing grain the TDN increased just slightly after that point.

Lamb performance started lower than expected then increased over time. This was a result of forage nutrient density and nutrient requirements for growing lambs. At 17% DM and 13% CP the lambs would have to eat nearly 7% of their body weight in DM...which is not possible for a 43 lb lamb. That would be nearly half their body weight in wet forage.

After forage samples were taken it was apparent that the poor the start was due to lack of nutrition for good gain as well as previous observations. Better gains were achieved when lamb weight and capacity increased as well as forage quality increased up to 21.4%DM and 17.6%CP allowing normal intake of 3-4% of their body weight to contain enough nutrients for acceptable gain.

Economics were figured on a cost to produce a pound of lamb. With a cost of approximately $350.00/acre each plot was figured on cost to produce a ton of forage on a DM basis. The value of lambs was averaged on a price of 80 lb feeder lambs being 1.15/lb. The average cost to produce a lb. of DM was about $.06. Intake at the beginning was 1.72lbs/hd/day costing $.10. Lamb gains were.10lb/hd/day valued at $.115 per day leaving $.015 profit per head per day. This is not including any other cost of production. Likewise when the higher gains of .38lbs per day the profit is close to $.32 per head per day with the best gains of .5lbs making $.42 /hd/day.

So is it profitable to graze the corn plant before it develops an ear??? That depends... The best option appears to be for lambs to be at least 65 lbs before they have enough capacity to eat enough green forage to allow proper nutrient intake.

One goal that was accomplished as stated before was the ability for lambs to stay parasite free during the grazing of the corn as long as back fencing is used only allowing lambs access to a three day grazing section at a time.

The project showed a couple key points. One being the corn did not make a nutrient dense enough feed for young (45 lb.) lambs. But when lambs reached 60 plus pounds gains were high enough to be economical. Another key point was proven to keep lambs parasite free thus reducing the dependency of chemical dewormers. A couple of interesting points that were observed but not measured were that corn will produce a lot of forage in the summer slump typically seen in grass/legume pastures in Southeastern Ohio. The summer was extremely hot and dry and most of the corn out produced grass pastures for production during that same time in the summer. Another positive for corn was its flexibility. Corn has several options to be harvested throughout the season unlike Sudan Grass and other summer annuals. Corn can be grazed in the summer before grain development, fall after grain development (silage stage), left for mechanical harvest, and let stand for winter grazing.

When used as a single goal forage grazing corn might not be the best forage available but with multiple goals put together in a grazing system corn can be the right forage for you.

• Corn Lamb spreadsheet
• lambs grazing corn
• lambs grazing corn
• corn forage spreadsheet
• lambs grazing corn