Effect of crambe meal on performance, reproduction, and thyroid hormone levels of
mature gestating and lactating beef cows¹

V.L. Anderson, J. S. Caton, and J. M. Kirsch
North Dakota State University
Carrington and Fargo

Abstract

Crambe meal was compared with a sunflower meal-soybean meal combination as protein supplements for mature beef cows in two experiments. In Experiment 1, mature beef cows (n=80, average wt 1435 ( 31.8 lb) were fed crambe meal at 9.86% of dry matter intake (DMI) during the last trimester of gestation. No differences (P<.05) were detected due to treatment for cow weight, condition score, thyroid hormones, calf birth weight or calving interval. In Experiment 2, mature crossbred beef cows (n=100, average wt 1248 ( 15.04 lb) were fed crambe meal at 7.44% of DMI intake during the last trimester of gestation and at 8.33% of DMI during early lactation. Gains were greater during gestation (P=.09) and overall (P=.06) and days to first estrus were reduced (P<.01) for cows fed crambe meal. During lactation, T3 levels did not drop as much for crambe meal cows (P=.03). No differences (P>.10) were apparent for condition score, calf birth weight, calf growth rate, weaning weight, thyroid hormones during gestation, and calving interval. These data indicate crambe meal is a useful protein supplement for beef cows.

¹ Research partially supported by USDA Special Grant No. 93-COOP-1-8669 and National Sun Industries, Inc., Enderlin, ND.

Introduction
Beef cows in the Northern Plains are often wintered on native range, low quality grass hay, or cropping system by-products such as straw and corn stover. These feeds often require supplemental protein to meet nutritional requirements (NRC, 1984). Protein is needed especially during the last trimester of gestation and during early lactation, before cows are turned out to graze. A variety of natural protein sources are available in the region.

Crambe is a relatively new industrial oilseed crop adapted to the region and processed in North Dakota (Gardner et al., 1992; Carlson et al., 1995). Crambe meal, the residue remaining after extraction of high erucic acid oil, must compete with other proteins for market share or be heavily discounted. Crambe meal has been investigated as a protein source for feedlot cattle (Anderson et al., 1998; Anderson et al., 1993; Stock et al., 1993; Perry et al., 1979; Lambert et al., 1970) with mixed to positive results. Glucosinolates contained in crambe meal and rapeseed meal have been implicated in trials where reduced palatability was observed (Carlson and Tookey, 1983; Fenwick et al., 1983). The predominant glucosinolate compound in crambe meal, epiprogoitrin (2 hydroxy-3-butynel) is known to be goitrogenic and affects thyroid hormone levels in rats (VanEtten et al., 1969).

No differences (P>.10) were observed in DMI, digestion of OM, ADF, or NDF when crambe meal was compared to soybean meal for steers offered low quality grass hay (Caton et al., 1994). Ruminal protein degradation rate was not affected by treatment indicating crambe meal and soybean meal have similar DIP/UIP values. No studies have been conducted using crambe meal in high forage diets for gestating and lactating beef cows. Objectives of this study were to determine the effects of crambe meal fed as a protein supplement to gestating and lactating beef cows on cow weight, condition score, thyroid hormones (T3 and T4), calf birth weight, days to first estrus, and calving interval.

Materials and Methods
Two experiments were conducted with genetically diverse herds at two separate locations. The same two supplemental protein formulations were used as treatments in both experiments. The supplements were formulated with either crambe meal (CM) or a sunflower meal-soybean meal-wheat midds combination as the control (CON, Table 4.1.). The CON supplement was 31.3% CP and CM supplement 32.1%. Degradable protein was calculated at 72.4% of CP for CON and 72.3% for CM. Crambe meal was partially dehulled prior to pre-press solvent extraction but fiber fractions were higher for CM supplement as a portion of the highly lignified hull remained with the meal. Neutral detergent fiber was 38.5% for CM and 32.6% for CON, ADF averaged 26.8% for CM and 18.5% for CON. Protein supplements were manufactured at the Northern Crops Institute Feed Mill, a feed manufacturing facility that routinely produces experimental supplements and rations for North Dakota State University.

The nutrient composition of CM averaged 95.1% dry matter, 34.5% crude protein, 41.3% neutral detergent fiber, 29.6% acid detergent fiber, 1.12% calcium, and .95% phosphorous (AOAC, 1990; Robertson and Van Soest, 1982). Glucosinolate content of crambe meal on an oil free basis was determined by the POS Pilot Plant Corporation Laboratory (Saskatoon, SK, Canada) according to procedures described by Daun et al. (1989). Total glucosinolate content of the CM was 63.5 umol/g (Miles Marianchuck, personal communication).

Table 4.1. Formulation and nutrient analysis of protein supplements fed to gestating and lactating mature beef cows (Experiments 1 and 2).

^a Treatments were supplemental protein sources from a combination of sunflower meal, soybean meal and wheat midds or from crambe meal.
^b UIP values for crambe meal adapted from Caton et al.,(1994), and
Stock et al., (1993).

Experiment 1

Eighty mature beef cows (avg. wt. 1435 ( 31.8 lb) were allotted to the two treatments on December 5 at the NDSU Animal and Range Sciences Department Beef Unit. Initial cow weight was calculated by averaging weights taken on two consecutive days. Cows within breed groups (purebred Angus, Shorthorn, Simmental, and Hereford) were randomly assigned to one of four pens with 20 cows per pen. Treatments were assigned to pens randomly. Diets were formulated supplements (Table 4.2) based on nutrient analysis of individual ingredients using corn silage, chopped wheat straw (4 inches), chopped grass hay (4 inches), and protein to meet NRC (1984) requirements for the third trimester of pregnancy and early lactation. Ingredients were sampled every 2 weeks and the analyses averaged for the period. Late gestation cow weight and condition scores were recorded on March 1. Blood serum samples were also collected as describe later.

Calving dates, calf birth weights, and calving dates the following year were recorded. Calving interval was calculated as the number of days from date of calving during this study to the date of calving the following year.

Table 4.2. Formulation of diets for gestating and lactating beef cows
(Experiments 1 and 2).

Table 4.2. (continued)

^a Treatments were supplemental protein from a combination of sunflower
meal, soybean meal and wheat midds or from crambe meal.

Condition score was determined (1 to 9 system, with 1 very emaciated and 9 very obese) by three independent scorers. The median number was used as the representative score. Final cow weight, condition score, and thyroid hormone data was recorded prior to parturition with rebreeding data reported only for cows nursing calves.

Experiment 2

Mature Hereford, Red Angus, and Tarentaise crossbred cows (n=100, avg. initial weight 1248 ( 15.04 lb) were randomly assigned to one of four pens with two pens per treatment and 25 cows per pen at the Carrington Research Extension Center. This experiment was initiated December 13 and protein supplementation continued until May 22 when cows are traditionally turned out to graze. In this trial, all pairs were maintained in drylot and fed a common ration to meet NRC (1984) requirement until weaning September 26. The supplementation period included an average of 53 ( 6 days of lactation. Protein supplements (Table 4.1, CON and CM) were fed in totally mixed diets (Table 4.2, 4.3) once daily in fenceline bunks. Gestation and lactation diets were fed at fixed levels in order to determine effects of crambe meal on performance and reproduction without the influence of variable intake. In addition to protein supplements, ingredients in the diet (Table 4.3) included corn silage, chopped wheat straw (2 to 4 inches), and chopped grass hay (2 to 4 inches). Condition scores and cow weights were taken as previously described at the start of the trial, prior to calving on March 7, after calving on May 22, and at the end of the trial on September 26. Weight and condition score changes were based on differences from December 13 to March 7 and May 22 to September 26. Calves were weighed at birth and at weaning. Blood serum was collected as described later, at the start of the trial on December 13, March 7, and September 26. Cows were observed for behavioral standing estrus to an androgenized mature cow each morning and evening from one month after the onset of calving until breeding season. Breeding dates were recorded starting June 6 for the duration of the 50 day natural service exposure. One mature bull was allotted per pen (25 cows) with a ration addition equivalent to 1.5 cows. The interval from calving to standing estrus was number of days to first estrus. Calving interval was calculated as describe previously.

Table 4.3. Nutrient analysis (DM basis) of diets fed to gestating and lactating mature beef cows (Experiments 1 and 2).

^a Treatments were supplemental protein from a combination of
sunflower meal, soybean meal and wheat midds or from crambe meal.
^b Calculated value (Caton et al., 1994, Stock et al, 1993, and NRC, 1996).

Thyroid hormone assay
Blood samples were collected by jugular veinipuncture using serum separator tubes (Becton Dickson Vacutainer Systems, Rutherford, NJ). Tubes were placed on ice until collections were complete and then centrifuged at 3600 x G for 20 minutes. Serum was aspirated and frozen at -20(C in glass vials for later analysis of total triiodothyronine (T3) and total thyroxine (T4). Thyroid hormones were quantified using radioimmunoassay procedures.

Statistical Analysis
General linear model procedures according to SAS (1996) were used to analyze the data. Pen was the experimental unit for cow performance, and individual animal for thyroid hormone and reproductive trait comparisons (Sokol and Rohlf, 1981). Main effects were cow weight change, condition score change, change in T3 and T4, calf birth weight, calf gain, weaning weight, days to first estrus, conception rate, and calving interval. Least squares means are reported with standard errors and P values associated with F test for the overall model.

Results and Discussion
Experiment 1

Crambe meal accounted for 9.86% of dry matter intake and glucosinolate concentration was 6.26 umoles/g of diet. No differences were observed for cow weight change, condition score change, calf birth weight, or calving interval (P>.10) due to treatment (Table 4.4). Gestation gains were 110.5 and 115.1 ( 11.95 lb for the 87 day period for CON and CM treatment groups, respectively. Condition score changes were identical (.24) and birth weights were very close at 100.8 and 101.2 lb for CON and CM groups, respectively. Crambe meal supported performance equal to the control protein supplement in every trait measured.

Higher than normal calf losses were experienced during and after parturition due to a variety of causes unrelated to the experiment. All post-partum data are from only those cows that calved successfully and nursed their calves to weaning. Calving interval (Table 4.4) was not different (P>.10) but was numerically shorter for CM cows at 364 days vs 374 days for CON. Thyroid hormones were not affected (P>.10) by treatment (Table 4.5). However both T3 and T4 decreased from mid-gestation to just prior to calving as observed by Hernandez et al. (1972). He theorized that maternal contribution of thyroid hormones to the fetus prior to parturition may reduce concentration in the dam's blood. Elevated post-partum thyroid hormone levels in the newborn calf dropped rapidly within a few days, suggesting this may be a mechanism for the calf to adapt to the extreme change in environment at birth.

Experiment 2

Crambe meal accounted for 7.44% of dry matter intake in CM cows during gestation and 8.33% during lactation. Glucosinolate concentrations were 4.72 and 5.29 umoles/g diet respectively.

Cow gains during the 87 day gestation period favored CM (P=.09) with 140.9 lb gain vs 150.6 for CON. Overall weight gain from December 13 to September 26 was also higher (P=.06) in CM cows at 36.9 vs 9.8 lb for CON cows (Table 4.6). Condition score changes were similar (P>.10) during gestation (.36 and .34), lactation (.41 and .38), and overall (.87 and .86) for CON and CM, respectively. Calf birth weight, gain, and weaning weight were not affected (P>.10) by treatment (Table 4.7). Natural service sires impregnated 87 and 89% of cows in CON and CM treatments respectively (Table 4.8). There were fewer d to first estrus (P<.01) for CM cows at 53 vs 67 days for CON. It is difficult to determine the reason for such a reduction in days to first estrus but this finding warrants further study. Cow gain may be a contributing factor with overall weight change favoring CM cows by 27.1 lb, however CS was not different.

Table 4.4. Weight and condition score of gestating beef cows fed a control or crambe meal protein supplement (Experiment 1).

^a Treatments were protein supplements from a combination of sunflower meal, soybean meal and wheat midds or crambe meal.
^b P value associated with overall F test.
^c Calving interval is number of d from date calved during this study to date calved the following year.
^d Treatment x replicate interaction (P=.06)

Table 4.5. Thyroid hormones in beef cows fed control or crambe meal protein supplements during gestation (Experiment 1).

^a Treatments were protein supplements from a combination of sunflower meal, soybean meal and wheat midds or crambe meal.
^b P value associated with overall F test.

Calving interval was 4 days shorter for CM cows but similar (P>.10) suggesting no direct or carryover effect into the lactation and rebreeding period. The reduction in performance described by several researchers for crambe and rapeseed meal (Perry et al., 1979; Lardy and Kerley, 1994; Papas et al., 1979; Pereira et al., 1981; Stock et al., 1993) and attributed to glucosinolate content must occur at dietary concentrations higher than fed in these experiments. Marginal iodine levels in the diet may also lead to earlier detection of changes in thyroid hormones (Papas et al., 1979). Iodine levels were not measured in this study, but no anecdotal data exists on deficiencies in the region.

Table 4.6. Weight and condition score of gestating and lactating beef cows fed a control or crambe meal protein supplement (Experiment 2).

^a Treatments were protein supplements from a combination of sunflower meal, soybean meal and wheat midds or crambe meal.
^b P value associated with overall F test.

Table 4.7. Performance of calves from cows fed a control or crambe meal protein supplement during gestation and early lactation (Experiment 2).

^a Treatments were protein supplements from a combination of sunflower meal, soybean meal and wheat midds or crambe meal.
^b P value associated with overall F test.

Table 4.8. Reproductive performance of beef cows fed a control or crambe meal protein supplement during gestation and early lactation (Experiment 2).

^a Treatments were protein supplements from a combination of sunflower meal, soybean meal, and wheat midds or crambe meal.
^b P value associated with overall F test.
^c Natural service sires, 1 bull per 25 cows in drylot, 50 day breeding season.
^d Number of d from parturition to first observed standing heat.
^e Number of d from date of calving during this study to date of calving the following year.

Table 4.9. Thyroid hormone levels in beef cows fed a control or crambe meal protein supplement during late gestation and early lactation (Experiment 2).

^a Treatments were supplemental protein from a combination of sunflower meal, soybean meal and wheat midds or from crambe meal.
^b P value associated with overall F test.

Crambe meal may have been processed differently in recent years resulting in reduced enzyme activity (Carlson et al., 1995) or increased volatilization of hydrolyzed products. The ability of the rumen to degrade glucosinolates has been observed (Duncan and Milne, 1991b; Majak, et al., 1991; Van Etten et al., 1977; Lanzani et al., 1974) but the presence of thioglucosidase, an enzyme that catalyzes hydrolysis a number of glucosinolates is required.

Even if the thioglucosidase enzyme is deactivated in processing crambe meal, it has been found to occur naturally in the lower gut of many mammals including swine and man (Orginsky et al., 1965). The hydrolysis breakdown product of most concern is 5-vinyl-oxazoladine-2-thione (OZT). This compound is thought to interfere with thyroxine (T4) synthesis (Astwood, 1949). With heat-toasting of the solvent meal, the enzyme may be deactivated resulting in a relatively palatable product. Fenwick et al. (1983) observed that OZT has a very bitter flavor and any substantial concentration may reduce palatability.

Possible reasons for lack of effect of crambe meal on thyroid hormones in this study include 1) less goitrogenic activity in the crambe meal due to different processing methods including heat toasting; 2) adequate dietary iodine content which may mask any goitrogenic effect observed by Papas et al. (1979); 3) absence of enzymes in the gastrointestinal tract to break down potentially goitrogenic compounds; 4) low concentration of crambe meal in the diet; or 5) maturity of animals at the start of the trial (Vincent et al., 1988). However, in our experiments, crambe meal was fed at levels higher than most producers would require for a balanced diet. We chose commonly fed low protein feeds to maximize amount of supplemental protein and increase the potential of observing effects of treatment.

Crambe meal has not been investigated as a protein source for breeding beef cattle prior to this study. Studies with rapeseed meal, which also contains glucosinolates, albeit a somewhat different profile may be useful comparisons. J. Seiverson, National Sun Industries (personal communication), laboratory supervisor observed solvent extracted high glucosinolate rapeseed meal contained 65.5 umoles/g 2-hydroxy-3-butenyl (epiprogoitrin), 35.0 umoles 3-butenyl, 10.8 umoles 4-pentenyl, and 6.7 umoles 2-hydroxy-4-pentenyl. Crambe meal in this study contained 63.5 umoles epi-progoitrin. Our results agree with observations in the U. K. where high glucosinolate rapeseed meal was used at 10% of cattle diets over a number of years without adverse effects (Cheeke, 1987). Ovarian cyclic activity and behavioral estrus were not affected at levels of 25 to 32.2% rapeseed meal in yearling heifer diets (Vincent et al., 1985). Ahlstrom (1978) observed high glucosinolate expeller rapeseed meal at 7.5% of the concentrate produced a small but significant increase in services per conception. Ingalls and Seale (1971) reported non-significant decreases in reproductive performance with high glucosinolate rapeseed meal at 27% of the concentrate with 9 cows per treatment. Similar results were reported by Lindell (1976) with 11 heifers per treatment and rapeseed meal fed for over one year. With 28 heifers per treatment, Emanuelson et al. (1987) reported number of days to first conception was longer for rapeseed meal (20 to 30 umoles/g) fed to heifers at up to 6.6 lb(hd-1(day. No effect on reproduction was noted in the second lactation. However, low glucosinolate rapeseed meal with glucosinolate intake of 31 g(hd-1(day was associated with increased days to first estrus, and reduced conception rates (Ahlin et al., 1985).

Rapeseed meal has produced mixed results in a number of studies on reproductive performance but numbers of animals are not large. With the results of these two studies on crambe meal involving 180 mature beef cows, we have concluded that solvent extracted crambe meal fed as a protein source at less than 9.86% during gestation and 8.33% during lactation has no negative impact (P>.10) on the bovine reproductive process.

Implications
Results of this study indicate that crambe meal is a useful protein source for beef cows during gestation and early lactation. Performance was equal or improved in every trait measured. At nearly 10% of dry matter intake, CM provided adequate protein to balance diets with large amounts of low quality forages during gestation. A shorter post-partum period to first estrus from CM and no negative effect on thyroid hormones gives producers and feed manufacturers confidence in using CM. The current competitive protein market where CM is lower priced per unit of protein provides further incentive for cattlemen to include CM in cow supplements. However, regulatory constraints will limit its use in breeding beef cow diets until additional research data is developed and appropriate petitions to FDA are successful.

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