Supplementation of Fall Calving Beef Cows in Central North
Greg Lardy1, Korry Hintze1, Trent Gilbery1, Joel Caton1, Brian Kreft2, and Dan Dhuyvetter3.
1Animal and Range Sciences Dept., NDSU, Fargo, North Dakota; 2Central Grasslands Research Center, Streeter, North Dakota; and 3Farmland Industries, Kansas City, Missouri.
Thirty-nine fall calving, crossbred cows (avg. initial BW = 1419 ± 134 lb) were used to determine the response to protein supplementation during early lactation (September through November). Following calving, cows were stratified by weight and allotted randomly into three treatment groups; control (CON, no supplement), rumen degradable intake protein (DIP) supplementation and DIP plus undegradable intake protein (UIP) supplementation. Supplements were based on wheat midds and sunflower meal. Blood meal and corn gluten meal were used to supply UIP. The DIP supplement was formulated to contain 24% crude protein (CP) and 70% DIP. The DIP+UIP supplement was formulated to contain 33% CP and 50% DIP. Cows were stanchioned every other day and individually fed the supplement for thirty days (4.4 lb/feeding). Supplements were formulated to provide equal levels of energy (based on total digestible nutrients) and DIP. Cows grazed native mixed-grass prairie for the duration of the trial. Difficulty was observed with consumption of all supplements early in the trial. Cow and calf weight change, cow body condition score change, four-hour milk production, milk fat percentage, and milk protein percentage were measured. Preplanned contrasts were used to compare the CON to the average of DIP and DIP+UIP and to compare DIP to DIP+UIP. Milk production and characteristics were not influenced by treatment (P>.10). Four-hour milk production averaged 3.7 lb. Cows supplemented with DIP+UIP had less body condition loss than DIP fed cows (P<.05). Calves nursing supplemented cows gained more weight than calves nursing non-supplemented cows (P<.005; 140.4, 158.0, and 156.4 lb for CON, DIP, and DIP+UIP respectively). These data suggest that protein supplementation of fall calving cows improves calf weight gain during October and early November.
Dormant grasses often do not meet the requirements of lactating cows (Hibberd et al., 1988). Cool season grasses may not contain sufficient UIP to meet the needs of lactating fall cows (Blasi et al., 1991). Providing supplemental UIP may alleviate this problem by increasing metabolizable protein to meet requirements for maintenance and lactation. Previous work with ruminally cannulated steers in south central North Dakota (Hirschfeld et al., 1996) showed that dietary crude protein (CP) levels on native range averaged 10.9% in October. Dietary UIP was not measured in that study.
Supplemental UIP for fall calving cows grazing dormant native range may be necessary to maintain cow body weight (BW), body condition, and to ensure rebreeding. Hibberd et al. (1988) demonstrated that UIP supplementation of fall calving cows reduced cow BW losses and increased calf weight and cow milk production.
Our objectives were to determine the effect of UIP supplementation on cow and calf weight change, cow body condition score (BCS) change, and milk production and composition.
Materials and Methods
Thirty-nine crossbred, fall calving cows, (initial weight 1419 ± 134 lb) were used to determine responses to protein supplementation during early lactation (September through November). Research was conducted at the Central Grasslands Research Center located near Streeter in south central North Dakota. Major forage species included Kentucky bluegrass, needle and thread, big bluestem, little bluestem, and western wheatgrass (Hirschfeld et al., 1996).
Following calving, cows were stratified by weight and allotted randomly to one of three groups: control (no supplement; CON), rumen degradable intake protein supplementation (DIP) formulated to contain 24% CP and 70% DIP, or DIP + rumen undegradable intake protein supplementation (DIP+UIP) formulated to contain 33% CP and 50% DIP. Degradable intake protein sources used were wheat midds and sunflower meal. Blood meal and corn gluten meal were used to supply UIP. Supplements were formulated to contain equal levels of energy (based on TDN) and DIP. Cows were individually stanchioned every other day and individually fed supplement for 30 days (4.4 lb/feeding).
Cow and calf weight, cow BCS, four-hour milk production, and milk composition were measured. Four-hour milk production was measured using a milking machine after injection with oxytocin (2 cc).
Four ruminally cannulated steers were used to collect masticate samples which were analyzed for neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein (CP), Acid detergent insoluble nitrogen (ADIN), and in vitro organic matter digestibility (IVOMD). Preplanned orthogonal contrasts were used to make the following comparisons: CON vs supplements, and DIP vs DIP+UIP.
Results and Discussion
Table 1 shows the crude
protein, ADF, NDF, and IVOMD of diet samples collected in
the pastures where the fall calving pairs grazed during the
study. Diet quality remained fairly high into November.
Table 1. Analysis of diet samples collected at Central Grasslands Research Extension Center during the fall of 1997. Values expressed on an organic matter basis (%, OM basis).
|Crude protein (CP)||9.3||8.9|
|In vitro organic matter digestibility (IVOMD)||50.6||50.9|
|Neutral detergent fiber (NDF)||80.1||83.8|
|Acid detergent fiber (ADF)||55.7||52.5|
|Acid detergent insoluble nitrogen (ADIN)||2.4||2.7|
Table 2 shows the effect of protein supplementation on cow weight gain, cow body condition score change, and calf weight gain. Cow weight change was not influenced by treatment (P = .23). Cows supplemented with DIP+UIP had less BCS loss than DIP fed cows
(P = .04). However, BCS
change was not different when CON was compared to the
average of the two supplemented treatments. Based on diet
sample analysis (Table 1), it is likely that cows were able
to meet their nutrient requirements on forage alone and did
not require supplementation to maintain body weight or
Table 2. Effect of protein supplementation on cow weight change, cow body condition score change, and calf weight gain.
|Cow Weight Change, lbs||-24.9||-42.6||-14.7|
|Cow Body Condition Score (BCS) Change||-0.2||-0.6||-0.2|
|Calf Weight Gain, lbs||140.4||158.0||156.4|
2UIP=undegradable intake protein
Calves nursing supplemented cows gained more weight than calves nursing CON cows (P = .002). This is similar to other research conducted with protein supplements for lactating cows grazing native range (Lardy, 1997).
Although treatment influenced calf weight gain, milk production and composition were not influenced by treatment (P = .49; data not shown). This is inconsistent with other work which indicates that protein supplements increase milk production (Hibberd et al., 1988). It is not clear why calf weight gain was greater for calves nursing protein supplemented cows when no differences in milk production or milk composition were detected. Calves were not given access to supplement in this study.
Supplementing protein to fall calving, lactating cows increases calf weight gain. Protein supplementation did not influence milk production or composition. Changes in body condition or cow weight were not influenced by supplementation.
Supplemental protein fed to fall calving cows will improve calf gains.
Blasi, D.A., J.K. Ward, T.J. Klopfenstein, and R.A. Britton. 1991. Escape protein for beef cows: III. Performance of lactating beef cows grazing smooth brome or big bluestem. J. Anim. Sci. 69:2294-2302.
Hibberd, C.A., R.R. Scott, B.D. Trautman, and C. Worthington. 1988. Bypass protein supplementation of fall-calving beef cows grazing dormant native range. Anim. Sci. Research Report 82-84.
Hirschfeld, D.J., D.R. Kirby, J.S. Caton, S.S. Wilcox, and K.C. Olson. 1996. Influence of grazing management on intake and composition of diets. J. Range Manage. 49:257-263.
Lardy, G.P. 1997. Protein supplementation of cows and calves grazing native sandhills range and subirrigated meadow. Ph.D. Dissertation. University of Nebraska, Lincoln.
North Dakota State University
Animal and Range Science Department
501 Hultz Hall
Fargo, ND 58105