Final Report for SW01-001
Eight studies were conducted to evaluate the effect of feeding whey silage on production and digestibility characteristics of growing and finishing cattle and beef cows. Whey silage was produced by combining cereal grain straw, wheat middlings and liquid whey. Growing cattle and beef cow ration costs were decreased significantly without affecting performance or feed digestibility when whey silage was the main or sole roughage source. There was no benefit for feeding whey silage to finishing cattle. These studies confirm that there are value-added opportunities for the use of these residue feeds for beef cattle.
1. Determine production and carcass characteristics of growing and finishing cattle and beef cows under maintenance conditions fed ensiled products that were derived from combining "sweet" or "acid" liquid whey, low-quality roughage sources and a concentrate source.
2. Determine nutrient content of these derived silage products.
3. Evaluate economics of production for whey silage compared to traditional corn silage-based diets and for cattle fed these silages.
4. Disseminate research results derived from these studies to beef producers, extension and industry personnel in the Intermountain West.
Growing cattle utilize roughage as the principle diet component, which can greatly influence the cost of production. Finishing cattle rations also contain a roughage component but to a much lesser degree than growing cattle. Beef cow diets usually consist exclusively of roughage. The utilization of less traditional roughage sources may decrease input costs for cattle producers. Cheese and yogurt manufacturing plants produce, as a by-product, liquid whey. Whey may be decanted or dried to various levels ranging from 8 to 45% DM. Small grain straw and wheat middlings (WM) are other residue feeds and are available in most areas of the United States. Combining these feedstuffs and then ensiling results in a preserved, palatable and nutritious feed. The literature is slight for reports of studies of this nature (ZoBell, 1985) although a few cattle producers have been using similar systems for many years.
Whey silage was produced in six separate growing (studies 1-4) and finishing (studies 7-8) and two beef cow trials (studies 5 and 6). Feedstuffs and proportions for the growing and finishing trials and beef cow trials are shown in Table 1. The liquid whey used for each study varied in dry matter percent and nutrient content (Table 1) and came from three separate manufacturing plants. Liquid cheese whey used in studies 5 and 6 were from the manufacture of yogurt, which is deemed "acidic." The liquid whey used in studies 1 through 4 and 7 and 8 were from the manufacture of various cheeses and were "sweet." All analyses reported in these studies were conducted at a commercial laboratory using AOAC (2000) standard procedures.
The ingredients were combined in a feed mixer for studies 1, 2 and 4 and packed in an open bunk silo. For studies 3, 5, 6, 7 and 8 the individual feedstuffs were combined in a feed mixer and placed in a silage bag. The whey silages were sampled 3-4 weeks later for nutrients, fermentation analysis and particle size (Tables 2, 3 and 4). Representative samples of each feedstuff were collected prior to and periodically during each of the studies for nutrient analysis.
Table 5 is a summary of the feedstuffs percentages (DMB) used for each treatment within each study. Cost of rations ($/ton DM) were: Study 1, C-$86.40, T-$52.49; Study 2, C-$72.31, T-$52.22; Study 3, C-$114.85, T-$84.87; Study 4, C-$118.35, T-$82.85; Study 5, C-$89.00, T-$46.00; Study 6, C-$55.96, T-$46.00; Study 7, C-$115.65, T-$106.77; Study 8, C-$122.56, T-$112.54. The whey silage costs do not include labor costs to make the silage.
Animal and pen numbers and initial weights for C and T groups are shown in Table 6. All studies, except trial 1 utilized British-based crossbred steer calves or cows (Table 7). Study l used growing Holstein heifers. The cows used in studies 5 and 6 were pregnant and fed under maintenance conditions to gain .23 kg/day. In the growing and finishing trials all calves had been processed similarly prior to trial initiation by receiving a Brucellosis vaccination, parasite treatment (Dectomax, Pfizer Animal Health, Exton, PA), 8-Way Clostridial vaccine (Pfizer Animal Health, Exton, PA) and intranasal respiratory product (BoviShield, Pfizer Animal Health, Exton, PA). Calves or cows were placed in pens and received rations as shown (Tables 1, 2 and 3). For all studies the C and T diets were isocaloric and isonitrogenous. Calves and cows were fed at 08:00 h such that there were no refusals. Individual calf and cow weights were recorded initially, every 28 days and at trial termination. Feed intake was recorded daily. Body condition score (BCS) and backfat (BF) measurements were taken initially and at trial termination for the beef cow studies (5 and 6). Live animal ultrasound using proprietary image analysis software was used for BF measurements and in trials 7 and 8 for BF, longisimus dorsi, and marbling (Brethour, 1991). Steers in trials 7 and 8 were slaughtered at the E.A. Miller Ltd (Hyrum, UT) facility and carcasses graded after a 24h chill.
The C and T diets that were used in studies 3 , 4, 5 and 6 were fed to four ruminally cannulated beef cows in digestibility trials using replicated 2 ¡Ñ 2 Latin square designs. Results from study 6 were not available for this report due to laboratory delays. Cows were individually housed in open front 4 m X 10 m pens with concrete floors. All feedstuffs were fed once daily at 08:00 h for a 21 d adaptation period followed by a 6-d collection period. Rations were fed at amounts that were totally consumed daily. During the collection periods, fecal grab samples (300 g) were obtained at 08:00 h from each heifer. Samples of the total mixed ration (TMR), feces and individual feedstuff samples were also obtained daily throughout the collection period. Feed and fecal samples were dried at 60ƒµ C for 72 h and ground in a Wiley mill to pass a 1 mm screen. They were then analyzed for DM (AOAC, 2000; 934.01), for total N using a LECO CHN-1000 Combustion Analyzer (Sweeeney, 1989; Yeomans and Bremmer, 1991), ADF and NDF using an Ankom Fiber Analyzer (Ankom Technology, Fairport, NY). The NDF was assayed without sodium sulfite, with alpha amylase, and without residual ash. Acid insoluble ash (AIA) (Van Keulen and Young, 1977) was used as an internal marker to estimate apparent nutrient digestibility. Feed samples were dried at 60 C for 72 h and ground to pass through a 1 mm screen and proportionately composited by cow for each of the two collection periods. Analysis of feed samples followed the same procedures and methodologies as those used for the fecal samples.
On day 6, ruminal fluid was obtained from the ventral sac of the rumen via the rumen cannula of each heifer at 0.1, 2, 4, 6, 8, 10 and 12 h after feeding and immediately analyzed for pH using a combination electrode. Rumen fluid was strained through eight layers of cheese-cloth and 2 ml of the fluid was acidified with 18 ml of 6 N HCL. Volatile fatty acid (VFA) concentrations were measured in acidified samples using gas chromatography (Hewlett Packard 5890, Avondale, PA) with a 1.83 m X 2 mm ID glass column packed with GP 10% SP-1200/1% H3PO4 on 80/100 mesh Chromosorb W-AW.
Statistical analyses were performed using the MIXED procedure of SAS (SAS Institute, Cary, NC). Performance data from the four trials, including ADG, DMI, and FE, were analyzed using a completely randomized design with a repeated measures treatment structure. Pen was the experimental unit with monthly sampling periods as repeated measures of feed treatments. Feed treatment, sampling period, and their interaction were fixed effects and pen was a random effect. Dry matter and NDF digestibility were analyzed as a replicated 2 X 2 Latin square design by using animals as the experimental units with periods of the Latin square incorporated as repeated measures of feed treatments. Treatment and period were fixed effects and animal was a random effect. Volatile fatty acid and pH data were analyzed using the same model, except hour of ruminal sampling was incorporated as an additional repeated measure. Sampling hour and its interaction with feed treatment were considered fixed effects. In all statistical models, the Kenward-Roger option was used to estimate denominator degrees of freedom. The variance-covariance matrix was chosen for each statistical model in an iterative process wherein best fit was chosen based on the Schwarz¡¦s Bayesian Criterion. Least squares means were estimated and separated using the pdiff option when fixed effects were significant.
Data from the growing trials showed that although DMI or ADG may have varied between trials, in all cases FE was not different between treatments (P>.05). This shows that the utilization of whey silage in high roughage diets for growing cattle has no effect on production variables. There was, however, generally a lower cost of gain for the growing cattle on whey silage (P<.05) due to the lower initial ration costs of the treated diets. Cost per kg of gain for the C and T groups respectively were: Study 1 - $.70 and $.35 (P<.05); Study 2 - $.51 and $.29 (P<.05); Study 3 - $.99 and $.77 (P<.05); Study 4 - $.77 and $.64 (P>.05).
Finishing cattle production variables also showed no difference in FE (P>.05). Ration costs between the C and T groups were very similar resulting in no difference in cost of gain. This would be expected in finishing diets comparing roughage sources as roughage makes up a small portion of the diet for these types of cattle. Cost per kg of gain for the C and T groups respectively were: Study 7 - $1.06 and $.99 (P>.05); Study 8 - $1.12 and $1.01 (P>.05).
Carcass data were also compared for ribeye area, backfat, quality grade, hot carcass weight and cutability between treatments for studies 7 and 8 and no differences for any of these variables was found (P>.05). This also would be expected as initial weights, ADG and days on feed between treatments were the same.
Results from studies 5 and 6 (wintering beef cows under maintenance conditions) showed that there was a significant difference between treatments (P<.05) for daily feeding costs. In study 5 daily feeding costs for the C and T treatments were $1.00 and $48.00 and $73.00 and $37.00 for C and T respectively in study 6 (P<.05). This is a reflection of the cost per ton of ration for T groups, which were much less than C diets. The higher costs of the C diet in trial 5 are due to high grass hay costs that year. In trial 6 a low-cost roughage diet was implemented that included half the diet barley straw which brought C diets down considerably compared to study 5. However, even with the low C ration cost in study 6, T cow daily feeding costs were one half of the C group (P<.05). Similar findings were found in study 5. Body condition score and backfat measurements indicated that C and T cows were of similar condition at trial initiation and termination (P>.05).
Results from the digestibility studies (Table 8) indicate that generally, whey silage diets were equally as digestible as those containing combinations of other roughage sources and feedstuffs such as alfalfa hay, barley straw and barley grain.
These studies demonstrated that a low-cost feed can be obtained when whey silage is produced. Growing cattle and beef cows under maintenance conditions fed whey silage have the greatest opportunity for profit as forage makes up all or a larger component of the diet. Additionally, digestibility was enhanced for straw when it was mixed with whey and wheat middlings and ensiled and fed as the major component of a growing diet. Cattle intended for slaughter, however, fed diets that included whey silage, had no economic advantage over those on standard finishing rations. Even though production variables were not decreased for finishing steers on whey silage a decision to incorporate whey silage into their diets would have to be made based on individual feedstuff prices.
These studies utilized a number of residue feeds available to cattle producers in the Intermountain West. These included liquid whey, cereal grain straw and wheat middlings. Combining the whey, straw and middlings added further value through the production of whey silage. This silage could be produced at any time of the year as the residue feeds are always available at competitive costs relative to other more traditional feedstuffs. The advantages and potential of whey silage have been studied in great depth through the eight studies that were conducted. The impact could be considerable once producers become acquainted with these ideas. Producers tend to be traditional in their approach to production practices but considerable interest has been generated by these studies and the dissemination of this information. Cow/calf producers could decrease winter feeding costs by 50% and producers who grow cattle could decrease their costs by 30%. This is very significant.
Education and Outreach
ZoBell, D.R.. E.K. Okine, K.C. Olson, R.D. Wiedmeier, L.A. Goonewardene, and C. Stonecipher. 2004. The feasibility of feeding whey silage and effects on production and digestibility in growing cattle. Can. J. Anim. Sci. (Submitted).
ZoBell, D.R., and C. Burrell. 2002. Producing whey silage for growing and finishing cattle. Utah State University Extension Publication AG514.
ZoBell, D.R., K.C. Olson, and R.D. Wiedmeier. 2002. Cheese whey silage for growing holstein heifers and beef finishing steers. J. Anim. Sci. Vol. 80, Suppl. 1/J. Dairy Sci. Vol. 85, Suppl. 1, p 235.
ZoBell, D.R., K.C. Olson, R.D. Wiedmeier, and C.A. Stonecipher. 2001. The effect of feeding a novel silage, consisting of liquid cheese whey and wheat straw, on production and digestibility characteristics of growing dairy heifers and beef steers. J. Anim. Sci. Vol. 79, Supp. 1, p 414.
ZoBell, D.R.. 2002. Cheese whey silage for growing beef cattle. Proceedings, Pasture Initiative. Utah State University, Field Day Report, May, 2002.
Education and Outreach Outcomes
Areas needing additional study
We recommend that more studies be conducted at other locales to determine if duplication of results can be achieved. There have been no studies in the U.S conducted on whey silage other than those reported here. This is unfortunate as it was difficult to determine if our results were similar to other investigators. Personal communication with dairy and beef producers in southern Idaho, who having been making whey silage for years on their own, provided some feedback and ideas. They have determined this to be a feasible feeding alternative and will continue with this practice.