Guillermo Scaglia | 10/10/2016 7:28:36 PM
Retaining calves in a stocker program seems to be a viable opportunity to add value to them. Most producers in the Southeast wean calves in the fall following spring calving and have the potential to increase calves’ body weight by using annual winter forages. Even more, producers on small farms (less than 60 acres) may benefit from strategic use of small areas of high nutritive value pastures, which may allow them to retain calves for marketing a few months later.
From a nutritional standpoint, annual ryegrass can provide up to 28 percent crude protein (depending on level of fertilization), which is approximately twice what a fall-weaned calf requires, with observed daily gains of 2 to 3 pounds; however, 60 percent of the nitrogen consumed by these calves is excreted in urine. This lack of efficiency might be corrected by limiting access to ryegrass while keeping cattle on low quality hay when off the pastures.
Before high-quality winter pastures become available, weaned calves are on a transition diet, which is usually made up of dry hay from bermudagrass or other summer grasses sometimes supplemented, as it must be done for this class of cattle, with a byproduct such as rice bran, corn gluten feed, soybean hull pellets or some other supplement that might be available close to the farm. This transition diet is lower in quality and less digestible than high-quality pasture, so when calves are transferred from the former to the latter, for approximately 15 to 20 days the animal and its rumen microbes (the “bugs” that are ultimately responsible for the degradation of the feed an animal consumes) need to adapt to this new diet. During this time, calves seem to lose weight and their excreta becomes very “watery.” Once this adaptation period ends and with appropriate grazing management, however, calves will perform well on these pastures.
Hay can make this transition period easier on calves. In the first 15 to 20 days of the grazing period, calves will consume some of the hay if it is available as a way to “self-medicate” themselves because of the change in diet. The calves’ “nutritional wisdom” makes sense because the hay will tend to retain forage particles in the rumen, thus increasing the probability of them being digested. Many producers provide hay in ryegrass pastures because of anecdotal information including “calves perform better,” “calves look healthier,” “hay helps extend the grazing season,” “hay is needed when calves run out of grass” and “we have been doing it for decades.”
The performance and grazing behavior of calves were compared on four treatments: 1) continuously stocked on annual ryegrass with no hay; 2) continuously stocked on annual ryegrass with hay; 3) stocked with access to ryegrass on alternate days with as much hay as they could eat when not on pasture; and 4) grazing on ryegrass for four consecutive days (96 hours) followed by three consecutive days (72 hours) only with access to all the hay they would eat.
Because the last two groups were on pasture only half of the time as those permanently on pasture, the area of ryegrass for the last two groups was half the size dedicated to the first two. This experiment was conducted for three consecutive years at the LSU AgCenter Iberia Research Station.
Table 1 shows animal performance in the different treatments. Steers grazing annual ryegrass with or without hay had a similar average daily gain and gained significantly more than steers that alternated grazing with hay (24 hours of grazing followed by 24 hours of hay). Those on annual ryegrass for 96 hours followed by 72 hours on hay gained significantly less than the other groups.
Hay consumption was estimated for those steers on pasture while steers not on pasture for one or three days were fed hay individually using electronic gates. Magnetic keys hanging from collars of these steers (Photo 1) opened small electronic gates, which could only be opened by one specific key, so the amount of hay each steer consumed was measured.
Steers that alternated grazing and hay every 24 hours ate more hay (5.1 pounds per head per day or approximately 1 percent of their body weight) than those that were in the barn for 72 consecutive hours (4.1 pounds per head per day; 0.8 percent of their body weight).
This hay consumption was low, which was noticeable for steers in the 96-hours-on-ryegrass/72-hours-on-hay group and explains their low overall average daily gain (Table 1). This may just have been a response to the quality of the hay. The level of crude protein approached the minimum requirement for rumen microbes to work efficiently, and fiber content was very high.
These factors may have contributed to what is called “rumen compaction,” which means the hay can’t be digested because the rumen “bugs” are not working properly and the rumen does not get emptied. This causes the animal to feel full and not eat enough hay or ryegrass. Better quality hay might be an appropriate choice.
Gains for the two groups that were continuously on ryegrass (with and without hay) were similar (Table 1). So, adding hay did not improve performance. Table 2 shows that from day one to day seven, when animals are getting adjusted to high-quality annual ryegrass, average daily gains were small because the steers were eliminating hay from their rumen and replacing it with their new diet, ryegrass.
After an additional week, their average daily gains are already more than two pounds and their adaptation is nearly complete. At this time we may still see “watery” feces, but this gradually will disappear.
From day 15 to 30, the animals are fully adapted, with the gains, in some cases above 3 pounds per day, explained by the so-called “compensatory gain.” Usually when cattle perform below their potential for a period of time because of low nutrition (for example, a hay-feeding period before grazing annual ryegrass), they will have greater gains immediately after their nutritional status is improved when placed on high-quality pastures. Compensatory gain is maximized when the time of low nutrition is not excessively long and gains during this period are not lower than half a pound a day.
Figure 1 shows the frequency at which steers were eating hay while they were grazing ryegrass. The data were obtained by observing all steers – three groups of six steers each – once every 30 minutes from 7 a.m. to 6 p.m. for 23 observations per day. A good number of the steers ate hay during the first few days because that had been their main diet for a few months and they had a familiarity with it. They also may recognize they need hay to help their digestion or supplement their new diet.
By day seven, the frequency of visits to the hay ring had diminished and remained low throughout the grazing season. The groups of steers grazing ryegrass with hay available never completely consumed the hay bale that was offered at the beginning of the grazing period. By the end of the experiment, bales look like the one in Photo 2; hence, the amount of hay that steers consumed during the grazing period was relatively small.
With appropriate grazing management – grazing system, stocking rate, forage allowance – and animal health care, there is no need to provide hay to stocker cattle grazing high-quality pastures. For a short period of time at the beginning they may look as they are losing weight, but this is an effect of changing the diet and reducing their gut fill. The cattle will gain well after this short period, and their overall performance will not be affected. Alternating grazing and hay feeding (24 hours by 24 hours) might be an alternative for small producers, but it certainly requires a close look to avoid affecting animal performance. Longer periods of feeding low-quality hay are not recommended; however, if hay or baleage from ryegrass or other annual grasses with or without legumes is available, it should be a good complement for this practice.
Guillermo Scaglia is a professor at the Iberia Research Station and beef cattle initiative coordinator for the Southwest Region.
Table 1. Average daily gains and productivity per acre for all 4 treatments (means of 3 years).
Photo 1. Steers on ryegrass for 24 hours and fed hay for 24 hours. Note the collar withg the key to open feeding gates. Photo by Guillermo Scaglia
Table 2. Average daily gains (pounds) of steers grazing ryegrass only or grazing ryegrass plus hay (means of 3 years). Day 1 is the first day of the grazing season, day 7, 14, 15 and 30 of grazing season thereafter.
Figure 1. Frequency at which steers were eating hay (from day 1 to day 28 of the grazing season) while they were grazing ryegrass.
Photo 2. Steers continuously stocked on ryegrass with hay. Note that the bale was not entirely consumed two weeks before the end of the experiment. Photo by Guillermo Scaglia
Photo 3. Steers grazing ryegrass with no hay approximately four weeks before the experiment ended. Photo by Guillermo Scaglia