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Water Intake a nd Factors Affecting Water Intake o f Growing Beef Cattle i n North Florida Megan Brew 1 Bob Myer Jeff Carter Matt Hersom Gary Hansen Summary A study was conducted to measure water intake in growing beef cattle, to determine what factors influence, and are influenced by, water consumption, and to compare observed intakes to predicted intakes. Growing bulls, steers, and heifers (n=146; average st arting weight of 607 lb) were housed in an open sided barn for a period of 13 wk from Sep 2006 through Dec 2006. Feed and water intake data was continually monitored by GrowSafe hardware and software. Cattle were weighed weekly. Mean water intake was 7.92 gal/d per heady or an average of 0.007 gal/lb of metabolic body weight (BW). Cattle of Brahman and Romosinuano breeding tended to consume less water than British and Continental influenced cattle at the same metabolic BW (P<0.05). There was no difference a mong bulls, steers, and heifers in either gross water intake or water intake per lb of metabolic BW. The mean daily temperature remained within the thermal neutral zone throughout the study and had no influence on water intake. Water intake was positively correlated (P<0.05) with feed intake and weight gain. There was no relationship between water intake and gain to feed ratio. Two common prediction equations were used to predict expected daily water intake. The predicted i ntakes were higher (P<0.05) than observed intakes. Introduction There has been very little research on beef cattle water intake. Water has been traditionally considered an inexpensive, readily available, and renewable natural resource. However, as human populations continue to soar, and m ajor cities continue to grow at nearly exponential rates, this may not always be the case in the future. W ater intake is poorly understood in beef cattle and differences that may exist between animals of different genders and breed types has not been clear ly defined. A number of prediction equations have been developed to help estimate expected water intake in dairy and beef cattle. However, the equations were developed under varying circumstances and may or may not be accurate for all classes of cattle. T he purpose of this study was to 1) measure water intake in growing beef cattle, 2) detect intake differences in water intake between animals of different genders and breed types, and 3) examine performance factors that affect or are affected by water intak e. Additionally this Water intake and the factors that affect water intake in growing beef were studied using a continuous data acquisition system. Water intake was positively correlated with average daily gain but had no relationship to feed efficiency. Established prediction equations were found to overestimate water intake
study tested the suitability of two prediction equations, the Mur p hy equation (Murphy et al., 1983) and the Hicks equation (Hicks et al., 1988), to predict water intake in growing Florida beef cattle. Procedures The study was conducted at the University of Center (NFREC) at Marianna in northwest Florida. Growing beef steers (n=61), heifers (n=74), an d bull calves (n=11) were housed at the NFREC Feed Efficiency barn for the duration of the study. This barn at the NFREC, Marianna, FL was designed for use with the GrowSafe TM system (GrowSafe Ltd, Airdrie, Alberta, Canada) and was used for this study. Eac h animal was fitted with a RFID ear tag prior to the beginning of the study. The pens in the barn are equipped GrowSafe TM feed bunkers and water troughs. Adjustable head gates allow only one animal to feed or drink at a time. When an animal inserts its h ead into the bunker or trough its RFID tag is automatically read by GrowSafe TM hardware. This system allows the measurement of feed and water intake of animals individually while being reared in groups. The barn is open sided and the pens have concrete flo ors; sawdust bedding was used. Twelve different breeds and breed composites were represented. Sire breeds used included Angus (AN), Brangus (BN), and Charolais (CH). Maternal breeds included BN, AN, Hereford x Angus (HFAN), Romosinuano (RS), Romosinuano x Angus (RA), Simmental (SM), Brangus x Hereford (BH,) and Simmental x Angus (SMAN). The resulting breeds and composites were; ANBN (n=13), BN (n=58), BNAN (n=13), BNHFAN (n=1), BNRS (n=18), BNRA (n=1), CHAN (n=8), CHBH (n=1), CHBN (n=15), CHRS (n=15), CHSM (n=1) and CHSMAN (n=2). Average starting weight was 607 147 lb/ head. Cattle were randomly assigned to pens of 15 to 20 head per pen. Cattle were allowed ad libitum access to a total mixed ration feed. The diet was composed of whole dry corn (38.0 %), soybean hulls (18.1%), cottonseed hulls (13.6%), Beefmaker 60 supplement (11.6%; Flint River Mills, Brainbridge, Ga), corn gluten feed (18.0%), and calcium carbonate (1%). The total CP was 17.3%, NEm was 0.16 Mcal/lb, NEg was 0.11 Mcal/lb, and Na was 0.12% Water was available ad libitum Following a two week adjustment period all cattle were weighed weekly (n=13). Ambient temperature was recorded by the Florida Automated Weather Network (FAWN) from the substation in Marianna. Data were analyzed using SAS version 9.0 (SAS Inst, Inc., Cary, NC). The experimental unit was individual animal, rather than pen, as GrowSafe TM allows for individual measurements to be recorded. Variables measured included water intake, feed intake, water intake adjusted for metabo lic BW feed intake adjusted for metabolic BW, average daily gain (ADG), and gain to feed ratio ( G:F). For the determination of the effect of breed/breed composite, only those groups with eight or more animals were used. U sing actual body weight, feed intake, feed composition, and weather data gathered during this study, the expected daily water intake for each animal was calculated using the Murphy et al. (1983) and the Hicks et al. equations (1988). These predicted intakes were then compared to actual intakes and means were separated Results Mean water intake (WI) was 7.92 2.26 gal/d per head When adjusted for metabolic BW, cattle drank an average of 0.007 0.002 gal/lb of metabolic BW. The cattle gained an average of 3.10 2.27 lb/d per head and G: F was 0.14 0.11 lb weight gain per lb of feed intake. The average daily temperature was 59 14 F and remained within the thermal neutral zone (40 to 70 F) for the duration of the study. When adjusted for metabolic BW, CHAN cattle drank significantly more than all other breed composites ( P < 0.05; Table 1). The BNAN cattle followed and drank m ore water per unit of metabolic BW than all other breeds except CHAN. The CHBN, BN, BNAN, CHRS and BNRS were similar ( P >0.05) in adjusted water
intake, drinking less than CHAN and BNAN cattle ( P <0.05). The BNRS cattle had the lowest intakes per unit of metabolic BW, but the average intake was not statistically different from average intakes of the CHBN, BN, BNAN, And CHRS groups. These results indicated that cattle with tropically adopted cattle breeding tended to consume less water than British and Continental influenced cattle at the same metabolic BW Bulls, heifers, and steers were all similar in both gross and adjusted water intake ( P >0.05; Table 2). Only a small number of bulls; however, were used in the comparison. Gross WI was related to ADG ( P <0 .0007) but was not correlated with G:F ( P =0.5677; Table3). Cattle who consumed greater quantities of water gained more weight overall ( P <0.05), but were not necessarily more or less efficient at doing so than cattle who consumed less water. When adjusted for metabolic BW, water intake was positively correlated with feed intake ( P <0.0001), feed intake per unit of MBW ( P <0.0001), and ADG ( P =0.0164). Once again there was no relationship between per unit of metabolic BW and G: F ( P =0.7556; Table 3). When run through a regression equation, ADG was found to be a function of water intake adjusted for metabolic BW (R 2 =0.005) with a weak linear relationship. Average daily gain was slightly more linear in relation to gross water intake (R 2 =0.009). The strongest linear relationships existed between feed intake and water intake (R 2 = 0.13), feed intake adjusted for metabolic BW and water intake adjusted for metabolic BW (R 2 =0.084), feed intake adjusted for metabolic BW and gross water intake (R 2 = 0.055) and feed intake and water intake adjusted for metabolic BW (R 2 = 0.014). The mean observed water intake for all cattle was 7.9 gal/d per head. The Hicks equation (Hicks et al., 1988) predicted that they would consume 10.1gal/d per head while the Murphy equation (Murphy et al., 1983) predicted an intake of 13.2 gal/d per head. Thus, these two equations overestimated intake ( P <0.05) by a factor of 2.2 and 5.3 gal/d per head, respectively. Literature Cited Hicks, R.B., F.N. Owens, D. Gill, J.J. Martin, and C.A. Strasia. 1988. Okla. Anim. Sci. Rpt. No. 125. Animal Sciences Dept, Oklahoma State University, Stillwater. pp 208. Murphy, M.R., C.L. Davis, and G.C. McCoy. 1983. J. Dairy Sci. 66:35 43. Acknowledgements The assistance of Meghan Brennan, Don Jones Harvey Standland, and Charles Nowell is greatly appreciated. 1 Megan Brew, former Graduate Student, Bob Myer, Professor, Jeff Carter, former Assistant Professor, and Gary Hansen, former Assistant Professor, UF IFAS, North Florida Research and Education Center, Marianna, FL; and Matt Hersom, Assistant Professor, UF IFA S, Department of Animal Sciences, Gainesville, FL.
Table 1. Water intake by breed Breed Gross water intake gal/d 1,2 Water intake per MBW 1,3 Charolais x Angus 11.2 a 0.011 a Angus x Brangus 8.5 b 0.008 b Brangus 8.1 b 0.006 c Charolais x Brangus 7.8 b 0.007 c, b Brangus x Angus 7.6 b 0.006 c Brangus x Romosinuano 6.4 c 0.006 c Charolais x Romosinuano 6.3 c 0.006 c 1 Within a column, means without a common superscript letter differ (p<0.05). 2 Gross water intake is expressed in gallons per head per day. 3 Water intake per MBW (metabolic body weight) is expressed as gallons per pound of metabolic BW per day per head. Table 2. Water intake by gender Gender Gross water intake, gal/d 1,2 Water intake per MBW 1,3 Bull 7.4 a 0.006 a Steer 8.1 a 0.007 a Heifer 7.8 a 0.007 a 1 Within a column, means without a common superscript letter differ (p<0.05). 2 Gross water intake is expressed in gallons per head per day. 3 Water intake per MBW (metabolic body weight) is expressed as gallons per pound of metabolic BW per day per head. Table 3. Significance (P Values) of correlations between water intake, fee d intake, weight gain and feed efficiency a FI FMB WI WMB ADG G:F FI <0.0001 <0.0001 <0.0001 <0.0001 0.0271 FMB <0.0001 <0.0001 <0.0001 <0.0001 0.0004 WI <0.0001 <0.0001 <0.0001 0.0007 0.5677 WMB <0.0001 <0.0001 <0.0001 0.0164 0.7556 ADG <0.0001 <0.0001 0.0007 0.0164 <0.0001 G:F <0.0001 <0.0004 0.5677 0.7556 <0.0001 a P values less than or equal to 0.05 are significant FI = feed intake per day FMB = Feed intake adjusted for metabolic body weight WMB = water intake adjusted for metabolic body weight ADG = average daily gain G:F = gain to feed ratio or feed efficiency