Journal of the NACAA
ISSN 2158-9429
Volume 11, Issue 1 - June, 2018


Effects of a Urea Based Hay Injection Treatment on Beef Cow Hay Intake and Forage Quality

Rivera, J.D., Associate Research/Extension Professor, South Mississippi Brach Experiment Station, Mississippi State University
Lemus, R., Extension Forage Specialist, Mississippi State University Extension Service
White, J.A., Forage Variety Testing Manager, Department of Plant and Soil Sciences, Mississippi State University


Three studies were conducted to evaluate the use of an injectable hay additive for improving both hay quality and feed preference by mature beef cows. In Experiment 1, six round hay bales (~849 lb) of mixed grass hay (bermuda/bahiagrass) were either injected with a hay additive at a rate of 3% of hay weight (INJ) or not injected (CON). Hay samples were collected prior to injection and at 4 days post injection. Samples were subsequently analyzed for nutritive content using Near Infrared Reflectance spectroscopy (NIR) to determine whether hay injection improved quality. In Experiment 2, twelve round bales (~862 lb) were randomly assigned to the same aforementioned treatments and used in a cafeteria style study by beef cows (n =112) to determine preference. In Experiment 3, four rates of injection (0, 3, 6, or 9% hay weight on a dry matter basis) were hand mixed into loose hay to determine if increasing levels of additive might improve nutritive characteristics. In Experiment 1, acid detergent fiber (ADF) was reduced (P = 0.03), and total digentible nutrients (TDN) was increased (P = 0.02) by the incorporation of INJ; no other effects were noted (P > 0.41). In Experiment 2, INJ did not improve any nutritive parameters compared to CON, nor did cows show a selection preference between INJ and CON (P > 0.61). In Experiment 3, higher rates of INJ resulted in lower ADF, neutral detergent fiber (NDF), greater crude protein (CP), TDN, and relative feed value (RFV) (P < 0.004). Results suggest some benefit may be derived from using a commercial injection, however those benefits may only be derived at greater than recommended rates.

Key words:  Hay additive, forage quality, beef cows.

Abbreviations:  Calcium (Ca), Phosphorus (P), Crude Protein (CP), Acid Detergent Fiber (ADF), Neutral Detergent Fiber (NDF), Total Digestible Nutrients (TDN), Relative Feed Value (RFV), Net Energy of Maintenance (NEm), Net Energy of Lactation (NEl), National Research Council (NRC), Body Weight (BW), Dry Matter (DM), Digestible Dry Matter (DDM), Dry Mater Intake (DMI)



Forage nutritive quality is an essential component of beef cow nutrition. In winter months producers rely on forages that had been harvested and stored over the previous season. According to the National Research Council (NRC) (2000) a mature cow (body weight [BW] = 1175 lb) has a requirement of between 8.54 and10.25% crude protein (CP) depending upon stage of production. In the lower South incorporation of cool-season annual pastures allows producers to supplement cow nutrient needs by grazing; however there is a period of time (transition period from fall to winter months) where warm-season forage crops have reduced quality parameters due to maturity (Ball et al., 2002), and cows at higher production levels (i.e. lactation or growth) will require some supplemental feed (NRC, 2016). While forage fed as hay is commonly utilized, Han and Tidwell (2014) demonstrated many Louisiana hay samples are below 8.54% CP and around 55% total digestible nutrients (TDN). Based upon the nutrient requirements of a lactating beef cow (NRC, 2016), hay of this type will not be adequate for the cow’s needs. In order to meet energy and crude protein needs, producers rely on supplemental feed (Kartchner, 1981; Chase and Hibberd, 1987). Direct supplementation of livestock feed (especially rumen degradable protein, RDP) can improve nutrient availability (Guthrie and Wagner, 1988). 

While benefits of supplementation have been demonstrated, many smaller producers are limited in their commodity feeds storage capabilities. This has led others to research other methods to deliver supplemental nutrients. Gilberry et al. (2006) determined that in lieu of feed supplementation, directly mixing condensed corn distillers solubles with low quality hay improved nutrient availably. Additionally, Brown et al. (1987) treated limpograss hay with three rates of ammonia and was able to increase digestibility and intake in beef cattle. Unfortunately, many small producers do not have access to anhydrous ammonia and corn distillers solubles may not be readily available due to ethanol plant location and transportation cost.  A commercially available product (Bale Boost 20, Haymaster Nutrition Injection Systems, Savannah, GA) has been marketed as a hay treatment to improve bale quality. The scope of this study was to determine whether this product improved hay quality and affected feed intake. 



All methods used in the following study were approved by the Mississippi State University Institutional Animal Care and Use Committee. All procedures occurred at the Mississippi Agricultural and Forestry Experiment Station, White Sand Unit, located in Southeast MS, approximately 10 mi west of Poplarville, MS (N30o47’, W-89o41’).

The hay injection treatment (INJ) used in the following experiments was a concentrate liquid that consisted of molasses, urea and mineral chelates designed to mix with water. The mix consisted of 20% CP (with 18% as non-protein nitrogen [NPD]), 0.75% Ca, 0.2% P and 40% dry matter (DM) (Bale Boost 20, Haymaster Nutrition Injection Systems, Inc., Savannah, GA) and was designed to be mixed with water at the rate of 2:1 (water:product). Per manufacturer’s recommendations, approximately 3 gallons of mixture was to be applied per bale. To equalize treatments and account for variation in weight, the average weight of all bales was determined, and the rate was determined as a percentage of bale DM weight for each injection. The calculated value was approximately 2.9% of bale DM weight. For facilitation of treatments the amount was rounded to 3%. The injection was applied using a hay injection apparatus, which consisted of three 4 ft. long hollow spears, with perforations around the circumference of each spear. Each spear was connected to a PTO driven pump, which was mounted to a liquid storage tank, with gradations indicating volume. The apparatus was mounted to a three-point hitch on a tractor, and the spears were backed into the bale, which allowed the spears to penetrate the face of the bale. Once the spears penetrated the bale, the pump was activated and the desired amount was pumped into the bale. The perforations were designed to provide for a uniform distribution of injection product inside of the bale. Due to the length of the spears on the injection apparatus, and per manufacturer recommendations, the application was done only on the bale face.

Experiment 1, Hay Quality. One week prior to the application of treatments, eighteen bales (840 + 50.4 lb, as fed basis) were individually identified, weighed and randomly core sampled (12 cores per bale) using 3 ft. core sampler. Samples from each bale were composited, and dried at 125 oF for 48 hours in a forced air oven for DM determination. Bales were a mixture of warm-season perennial grasses common to southern Mississippi and consisted of bahiagrass (Paspalum notatum Flugge) and common bermudagrass (Cynodon dactylon Pers). After 7 days, bales were randomly assigned to treatments, which consisted of INJ at 3% of hay weight (DM basis) or no injection (CON). The previously obtained core samples were ground to 2 mm (Wiley Mill, Thomas Scientific), and subsequently analyzed for forage quality using a FOSS 6500 Near Infrared Reflectance (NIR) System (Foss North America, Eden Prairie, MN). Forage quality parameters (CP, acid detergent fiber [ADF], neutral detergent fiber [NDF], Ca, and P) were determined using the 2012 hay equation developed by of NIRS Forage & Feed Testing Consortium (Hillsboro, WI). Following treatment application, bales were stored side by side outside. Four days after treatment, core samples were again obtained from all bales and subjected to all previously mentioned NIR analyses. Data were analyzed using the MIXED procedure of SAS with bale as the experimental unit. Fixed effects were treatment and time (pre and post injection) and the interaction between the two. Least squares means were considered significantly different at P < 0.05. Total digestible nutrients (TDN) were calculated using the following formula: 81.38 + (CP x 0.36) – (ADF x 0.77) (NRC, 2001). Relative feed value (RVF) was calculated using DDM x DMI /1.29, where DDM is 88.9 – (0.78 x ADF) and DMI was calculated as 120/NDF (Cumberland Valley Analytical Services,

Experiment 2, Hay Intake. Bales that had previously been treated in Experiment 1 were used to determine intake in a cafeteria-style selection study. Beef cows (2-3 months post-partum, average body weight 1275 lb.) from the White Sand Unit breeding herd (commercial crossbred cows, primarily English with minor Brahman influence) were separated into three breeding groups. Group 1 (n = 35) consisted of younger cows (3-5 years old) and Groups 2 and 3 (n =35 and 42, respectively) consisted of older cows (6 years and greater). Each group was maintained in a 24 acre dormant pasture of bahiagrass and common bermudagrass that had been grazed down the previous fall, so very little forage biomass was remaining. Adjacent to the dormant pastures were 12 acre pastures of annual ryegrass (Lolium multiflorum). Annual ryegrass had been drilled into prepared seedbeds at the rate of 35 lb/ac the previous fall, and all pastures were treated with 250 lb of NPK (17-17-17) per acre. Within each of the dormant pastures, four ring bale feeders were placed equidistant from the gate and from water sources. Starting at 10 days post injection, four bales were selected (two CON and two INJ), individually weighed, core sampled, and randomly placed in the four ring feeders within each pasture. This was repeated across all three pasture groups. It was noted that in some instances, some of the INJ had leaked from the bale and was observed to be on the ground. Cows were allowed to graze annual ryegrass for 4 h each day, then moved into the pasture and allowed free choice access to bales. In each group, cattle were monitored for 10 minutes following turn out to see which bales cows seemed to initially prefer. After 4 days, the remaining bales and all loose hay around each feeder were collected, weighed and a grab sample was collected for DM analysis to calculate intake over the 4 day period. After a 7 day wash out period, the entire process was repeated again. Amount of hay offered, refused and calculated DM disappearance were estimated. Data were analyzed as a Mixed Model using SAS with treatment a fixed effect. Block and period were considered random effects. Significance was declared at P < 0.05. 

Experiment 3, Graded Levels. This experiment was conducted to examine whether increasing the amount of additive would improve nutritive value. Sixteen plastic round tubs (19 inches in height x 24 inches in diameter) were filled with approximately 7 lb of loose hay from a single round bale of mixed bahiagrass/bermudagrass hay. Each tub was randomly assigned to one of four treatments, 0, 3, 6 and 9 % of INJ per weight of hay (DM basis) to correspond to 0, 1, 2 and 3 times the recommended injection rate. The INJ treatment was mixed as described previously and poured onto each hay sample. Samples were then thoroughly hand mixed to ensure uniform distribution. After a 72 hour period, random grab samples were obtained from each tub (approximately 1-1.5 lb), dried in a forced air oven (125 oF for 48 h), ground through a 2 mm screen (Wiley Mill, Thomas Scientific) and subsequently analyzed using NIR technology as described in Experiment 1. TDN and RFV were also calculated in the same manner. Data were analyzed as a randomized complete block using PROC MIXED. Treatment was considered fixed, and when the overall model was significant (P < 0.05) least square means were separated using PDIFF. Orthogonal polynomials were used in contrast statements to determine linear, quadratic or cubic responses to treatments. 


Experiment 1, Hay Quality. Results of Experiment 1 are noted in Table 1. While it was not quantified, it was noted by personnel that during the injection process some of the injection leaked out of the bales, which may have influenced the results. The application of INJ decreased the percent ADF following injection (P = 0.03). It is unclear how the application of INJ would decrease ADF. Brown (1993) noted no differences in ADF following ammoniation of stargrass (Cynodon aethiopicus) hay. Additionally, percentage TDN was increased post injection (P = 0.12). The equation used to calculate TDN had percentage ADF as a factor, which may explain the observed effect. Relative feed value also tended to be improved following injection (P = 0.12). Similar to TDN, RFV is a percentage of ADF and might be the reason behind this tendency. No other injection effects were noted (P > 0.05) for any other forage quality parameter.


Table 1. Effects of a hay injection product (INJ) on forage nutritive value of round bales before and after application of treatment. Pre-injection were sampled prior to application of 3% of INJ per weight of bale. Post-injection were collected 4 days following injection.  

 Item (DM Basis) Pre-Injection Post-Injection SE P Value
 Acid Digestible Fiber (ADF), % 44.30 43.40 0.320 0.03
 Total Digestible Nutrients (TDN), % 49.94 50.80 0.270 0.02
 Relative Feed Value (RFV), % 70.62 72.00 0.620 0.12
 Neutral Detergent Fiber (NDF), % 71.51 71.14 0.590 0.63
 Crude Protein (CP), % 7.50 7.88 0.400 0.48
 Ca, % 0.52 0.51 0.020 0.87
 P, % 0.18 0.19 0.004 0.41



Experiment 2, Hay Intake. No differences were noted between CON and INJ for any parameter measured (Table 2). Similarly McCormick et al. (2011), using the same product, noted that injection did not improve the quality of either bermudagrass hay or Johnson/crabgrass hay. In contrast, Grotheer et al. (1985) was able to increase digestibility of hay with ammonia treatment. However, it should be noted the ammonia treatment resulted in greater N applied compared to the present study. Ortigues et al. (1988) increased CP by injecting a 32% CP urea/molasses liquid supplement into corn stover and fescue round bales. They also noted poor distribution of the injection throughout the bale, which may have occurred in the present study. As noted with Grotheer et al. (1985), the injections used by Ortigues et al. (1988) resulted in greater addition of CP compared to the current study. It should be noted that the liquid supplement used by Ortigues et al. (1988) was applied at a higher rate compared to INJ in the present study, which might account for the differences noted. Additionally, Ortigues et al. (1988) noted that there was some loss of injection from the bale, similar to what was observed in the present study. Previous studies have shown that ammoniation of hay (Brown, 1991) can improve the quality; however, this application usually occurs at baling and over a long period of time. Additionally, Brown (1991) did not show any improvement in ADF. Similarly, (Krueger et al., 2008) showed improvement in hay quality and animal performance. Krueger et al. (2008) used ammonia treatment at 3% of DM of bale, while in the current study we used additives at approximately 3% of DM of bale, however, the overall N of the injection used in the current study was approximately 50% lower than ammonia used by Krueger et al., (2008). Moreover, ammonia treatments were applied by spraying on top of bales, bales were covered and allowed to react with ammonia for 6 wk prior to feeding.

No differences were noted in DM consumption between CON and INJ (P = 0.61). In contrast, McCormick et al. (2011) observed an effect with regards to preference for hay treated with an injection similar to the one used in the present study compared to untreated hay fed to yearling Holstein heifers. It should be noted that the bales fed in McCormick et al. (2011) were fed immediately after injection while in the present study bales were fed at 10 and 22 days post-injection. Perhaps the mixture was still fresh enough to allow for olfactory detection by the heifers used by McCormick et al. (2011). Similarly, Miller et al. (2005) noted that dry matter intake (DMI) in sheep was increased with molasses fortification of native hay of lower nutritive quality. Those intake differences might be attributed to the higher level of molasses inclusion which was almost 6 fold greater than the INJ used in the present study. While DMI was not measured, Ortigues et al. (1989) found that stocker performance was improved when they were able to consume the molasses/urea supplement from a lick tank rather than the supplement injected into the hay.  Ortigues et al. (1989) theorize that the poor distribution of their injection coupled with their losses, might have resulted in a reduced performance response. Despite some leaking of the injection from the bales following application, observed in the present study, calculated CP was 7.86%, which is very similar to NIR derived values; therefore, we must assume that an adequate job of distributing the injection was done.


Table 2. Effects of injection on hay quality parameters. Treatments were application of a commercial hay additive at the rate of 3% of bale weight (INJ), or no application (CON).

Item (DM Basis) Control Injection SE P Value
ADF, % 43.96 43.40 0.560 0.18
NDF, % 71.50 71.14 0.730 0.63
CP, % 7.71 7.88 0.500 0.74
TDN, % 50.19 50.91 0.480 0.16
Ca, % 0.52 0.51 0.020 0.73
P, % 0.19 0.19 0.005 0.49
DM offered, lb 754.11 748.45 8.450 0.65
DM refused, lb 237.48 249.39 25.180 0.75
DM consumed, lb 516.63 499.21 23.560 0.61



Experiment 3, Graded Levels. Increasing the amount of additive administered to bales resulted in linear decrease in ADF concentration (P = 0.004) (Table 3). Similarly, CP concentration increased as well. Ortigues et al. (1989) noted that CP increased with a 12% inclusion of a 32% CP supplement. Increasing N in a molasses N hay treatment did not result in increased organic dry matter digestibility by Miller et al. (2005). In a like manner, percentage NDF decreased in a linear fashion (P = 0.0002). Not surprisingly, percentage TDN and RFV had a linear increase (P = 0.0001 and P = 0.0003 for TDN and RFV, respectively), since both of those calculated values were composed of the aforementioned nutritive values (CP, ADF and NDF). As the amount of injection increased, it should be expected that forage nutritive values improve, however, based upon the results of the present study, levels at 3 times the recommended rate resulted in improved nutritive values which might be difficult to replicate in a production setting. As previously mentioned in the prior experiments, leakage following injection associated at recommended levels from hay bales may have impacted the study. Commercial costs for the hay treatment is approximately $0.86/gallon therefore, costs were approximately $7.50 per bale for the 3% treatment. To reach the level where we had consistent response in terms of improving quality, that cost would be $15.00 per bale. 


Table 3. Forage quality of hay treated with graded levels of INJ. Treatments were: INJ applied at the rate of 0, 3, 6, 9 % of hay weight and hand mixed. 

  Treatment   Contrastsa
Item (DM Basis) 0 3 6 9 SE L Q C
ADF, % 42.81y 41.45z 40.47z 40.54z 0.50 0.0040 0.18 0.77
NDF, % 70.18x 67.10y 64.79z 63.97z 0.88 0.0002 0.23 0.86
CP, % 10.50x 10.85x 11.89y 12.85z 0.41 0.0009 0.47 0.67
TDN, % 52.20 53.36 54.50 54.79 0.37 0.0001 0.26 0.63
RFV, % 73.68 78.43 82.37 83.37 1.47 0.0003 0.23 0.75

bContrast analysis is represented by linear (L), quadratic (Q), and cubic (C) comparisons to test treatment interactions within each forage quality parameter.

x,y,zLSMeans without a common superscript differ at P < 0.05.



Data from the current project determined that use of a 20% CP urea/molasses hay treatment did not improve quality or stimulate intake in beef cows when applied at a 3% of hay weight on a DM basis. When hand-mixed at higher rates, the results were less variable, with higher rates resulting in greater nutritive value. It is unclear whether the higher rates when applied to round hay bales via the commercially recommended method would result in greater losses of injection materials. 



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This publication is a contribution of the Mississippi Agricultural and Forestry Experiment Station. Additional funding for the project came from the Mississippi State University William White Special Project award. The authors gratefully acknowledge M. L. Gipson, R. G. Gipson, and P. J. Slusher for technical assistance, as well as Hay Master Systems for donation of equipment and supplies used in the project.



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