WHOLE COTTONSEED AND COTTON TEXTILE MILL WASTE IN
SORGHUM SILAGE-BASED DIETS FOR DEVELOPING HEIFERS
Introduction
The acreage of cotton grown in North Carolina has increased in recent years,
increasing
the supply of whole cottonseed available to cattlemen. In three of the last four years,
whole
cottonseed has been avail able at less than $100/ton FOB gins, which is well below the
actual
value of it's nutrients of about $140/ton. Cottonseed is also conveniently handled and
requires no
processing, making it a very desirable feed that has been rapidly adopted. Because
most cow calf
producers using whole cottonseed also want to feed it to their replacement heifers, and
because
of the growing stocker sector in the state, we have received many questions regarding
the optimal
use of whole cottonseed for growing cattle. Several previous studies conducted have
suggested
that cottonseed should be limited to less than 15% of diet dry matter, but additional
information
is needed to strengthen this recommendation.
Cotton textile mill waste is short fiber cotton resulting from the processing of raw
cotton
into yarn. This is another alternative feed available to North Carolina cattlemen that is
available
in some areas, but again, information on which to base feeding recommendations is
limited. This
trial was conducted to evaluate the effect of altering the level of whole cottonseed in
sorghum
silage-based diets with or without the cotton fiber added. This design allowed not only
the
evaluation of cottonseed level and cotton fiber, but also whether the type of fiber
present in the
diet would alter the influence of cottonseed.
Materials and Methods
Sixty M-1 Angus heifers purchased from North Carolina Graded Feeder Calf Sales
were
used in the 84-day trial. They were fed total mixed rations through Calan feeding gates
at the
Butner Beef Cattle Field Laboratory during the winter of 1992-1993. The diets
contained on a
dry matter basis either 67% sorghum silage and 33% concentrate or 47% sorghum
silage, 20%
cotton fiber, and 33% concentrate. Soybean meal, ground corn, and whole cottonseed
were
included in the concentrates such that each type of diet had either 0, 6, 12, 18 or 24%
whole
cottonseed , giving a total of 10 different diets and six heifers per individual diet. Diets
were
formulated to meet protein and mineral requirements, and were predicted to provide 2
lb/day
gain.
Shrunk weights were obtained on the heifers at the beginning and at the end of the
trial to
determine gain. Initial weight of the heifers was 541 lb, and feed intake was monitored
daily.
Near the mid point of the trial, rumen samples were withdrawn by stomach tube 2 hours
after the
morning feeding to evaluate ruminal ammonia and VFA levels, and blood samples were
obtained
at the same time to evaluate blood urea nitrogen levels.
Results and Discussion
There were few interactions between whole cottonseed level and the addition of
cotton
fiber, so only main effects are reported here. The main effects of cottonseed level and
cotton
fiber on growth, intake, ruminal ammonia and blood urea nitrogen are shown in Table 1, while ruminal VFA level and proportions are
shown in
Table 2. Dry matter intake and average daily gain
were not
influenced, while feed efficiency was improved when 20% cotton fiber was substituted
for
sorghum silage. Blood urea nitrogen was decreased and ruminal ammonia was
increased
indicating that there was some effect of the cotton fiber on ruminal nitrogen metabolism.
Ruminal VFA were also influenced by the cotton fiber in that total VFA was higher, and
the
proportion of propionate, isobutyrate, butyrate, and isovalerate were lower in diets with
cotton
fiber. This result indicates that while the textile mill waste may influence the ruminal
environment, it has great potential as a feed, and appears to have a nutritional value
similar to
sorghum silage.
Increasing cottonseed level linearly decreased dry matter intake and average daily
gain of
the heifers with what appeared to be a break between the 12 and 18% levels. Feed
efficiency
was not effected by cottonseed level. At the highest level of whole cottonseed, heifers
fell well
short of the rate of gain needed to meet the target weight for breeding. The reason for
this
negative effect of cottonseed is not clear but could be due to several factors. The oil
present in
the cottonseed could have negative effects on ruminal function, but earlier studies have
indicated
that even the fat content of the 24% cottonseed diets should not have caused a
problem. Another
possibility is that the toxin gossypol present in cottonseed could have been involved.
The
cottonseed used contained 1.15% total gossypol, a substantially higher level than
reported for
cottonseed produced in other areas of the country. The level of gossypol consumed by
the
heifers in the 24% cottonseed diet (18.4 grams/head/day) was near the level known to
cause
some subclinical toxicity, but depressed feed intake and growth rate have not been
reported at
this level. Additional research is being conducted to understand the reason for this
reduction in
feed intake and growth rate. It is recommended that due to the importance of obtaining
predictable
perfor mance in developing heifers and stocker cattle, cotton seed should be limited to
15% of
the diet, or about 2.5 lb/head/day.
Conclusions
Cotton textile mill waste substituted for sorghum silage had no negative effect on
performance of these heifers, indicating that it has potential as a feed ingredient in this
type of
diet. Increasing whole cottonseed decreased gain in diets with or without cotton fiber.
The
break appeared to occur between 12 and 18% whole cottonseed, and this supports the
recommendation of limiting whole cottonseed to 15% of the diet for growing cattle.
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