We conducted two experiments evaluating perennial ryegrass straw as a forage
source for ruminants. Experiment 1 evaluated digestion and physiological variables in
steers offered perennial ryegrass straw containing increasing levels of lolitrem B.
Sixteen ruminally cannulated Angus X Hereford steers (231 ± 2 kg BW) were blocked
by weight and assigned randomly to one of four treatments (TRT). Steers were
provided perennial ryegrass straw at 120% of the previous 5-d average intake. Prior to
straw feeding, soybean meal (SBM) was provided (0.1% BW; CP basis) to meet the
estimated requirement for degradable intake protein. Low (L) and high (H) lolitrem B
straws (<100 and 1550 ppb, respectively) were used to formulate TRT diets: LOW
(100% L); LOW MIX (67% L:33% H); HIGH MIX (33% L:67% H); HIGH (100%
H). Intake and digestibility of DM and OM, and ruminal pH, total VFA, and NH₃-N
were not affected by increasing lolitrem B concentration (P>0.13). Ruminal
indigestible ADF (IADF) fill increased linearly (P=0.01) and IADF passage rate
(%/h) decreased linearly (P=0.04) as lolitrem B level increased. Experiment 2
evaluated performance and production of 72 Angus X Hereford cows (539 ± 5 kg
BW) consuming perennial ryegrass straw containing increasing levels of lolitrem B
during the last third of gestation. Cows were blocked by body condition score (BCS)
and randomly assigned to one of three TRT. Cows were provided perennial ryegrass
straw ad libitum and supplemented with SBM (0.1% BW; CP basis) to meet the
estimated requirement for degradable intake protein. Mixtures of a L and H lolitrem B
straw (467 and 2017 ppb, respectively) were used to formulate TRT diets: LOW
(100% L); MIX (50% L:50% H); HIGH (100% H). Thirteen of 24 cows on the HIGH
TRT exhibited signs of ryegrass staggers and were removed from the study. Dry
matter intake was not affected (P>0.12) by increasing lolitrem B concentration;
however, estimated DM digestibility decreased linearly (P<0.01) as lolitrem B
concentration increased. Lolitrem B concentration did not influence pre- or post
calving weight or BCS change (P>0.10). These data suggest that feeding perennial
ryegrass straw containing up to 1550 ppb lolitrem B does not adversely affect nutrient
digestion or physiological response variables in steers. However, providing straw with
a lolitrem B concentration of approximately 2000 ppb resulted in 54% of cows
exhibiting signs of ryegrass staggers. Blending of H and L straws appears to be a
successful management practice.
Keywords: Alkaloid, Beef Cattle, Endophyte, Lolitrem B, Perennial Ryegrass, Straw / Graduation date: 2004
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/30046 |
| Date | 28 July 2003 |
| Creators | Fisher, Michael J. |
| Contributors | Bohnert, David W. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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