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Department of Animal Sciences, The Ohio State University, Wooster 44691
2 Correspondence:
1680 Madison Ave. (phone: 330-263-3900; fax: 330-263-3949; E-mail:
loerch.1{at}osu.edu).
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Abstract |
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 Top Abstract IntroductionMaterials and MethodsResultsDiscussionImplicationsLiterature Cited |
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Key Words: Beef Cows • Corn • Forage • Restricted Feeding • Stockpiling
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Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionImplicationsLiterature Cited |
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionImplicationsLiterature Cited |
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From November to February of 1998 to 1999, 1999 to 2000, and 2000 to 2001, 31, 24, and 17 mature, pregnant Simmental x Angus cows (initial BW = 662.0 ± 10.4 kg) from the Coshocton branch of the Ohio Agricultural Research and Development Center (OARDC) were used to determine the efficacy of limit-fed corn, stockpiled orchardgrass, or ad libitum orchardgrass hay for maintaining cows in mid- to late gestation. Hay was approximately 67.2% NDF and 12.9% CP. Cows were randomly allotted to the three groups. Groups were subsequently balanced for starting weight and age. Cows were reallotted to treatments and a small percentage were culled and replaced every year. Cows limit-fed corn were wintered in a 2-ha drylot and were fed approximately 5.8 kg of whole shelled corn, 1.1 kg of a pelleted supplement, and 1.2 kg of orchardgrass hay daily. Diets were formulated to meet or exceed cow nutrient requirements (NRC, 1996), thus the amount of corn provided was increased in December to compensate for energy needs in cold environmental temperatures and increasing cow requirements in late gestation. Square-baled orchardgrass hay was fed throughout the winter feeding period to ensure that rumen health was not compromised. Cows were fed hay and grain once daily, and 0.6 m of bunk space was provided per cow. A 4-d adjustment period, in which hay was gradually decreased to 1.14 kg•cow-1•d-1, was used to acclimate cows to the corn-based diet. Supplement was prepared at OARDC, and its composition is provided in Table 1
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Cows fed orchardgrass hay were wintered in a 21-ha pasture. The pasture was dormant during the trial, and available forage was removed by grazing prior to the initiation of the trial. Cows were fed round-baled orchardgrass hay ad libitum in a hayrack. Hay bales were weighed prior to feeding. Hay intake data reported reflect hay that was offered because this represents the cost of feed. Hay wastage was approximately 10%, but this was not quantified. Hay was primarily first-cutting orchardgrass. Core samples were taken from random bales and nutrient analysis was performed. Cows grazing stockpiled orchardgrass and cows fed round-baled hay were also provided with ad libitum access to a salt and mineral mix (29.5% trace mineralized salt, 25% dicalcium phosphate, 25% magnesium oxide, 10% limestone, 10% ground shelled corn, 0.5% ethylene diamine-dihydroiodide, and 50 ppm of selenium).
Feed costs were calculated using the following prices: corn = $0.079/kg ($2.00/bu), hay = $0.088/kg ($80/ton), and supplement = $0.165/kg ($150/ton). Pasture rental costs were determined using the alternative feed method (Langemeier, 1997), where monthly pasture rent per hectare = average starting weight per 454 kg of the animals x average price per 909 kg (ton) of good grass hay x pasture quality factor. Daily pasture rental cost per hectare was multiplied by stocking rate (cows/ha) to arrive at daily pasture rental cost per cow.
Feeds were analyzed for DM (AOAC, 1996), ADF, and NDF (Goering and Van Soest, 1970). Nitrogen (N) content was determined using a combustion-type N autoanalyzer (Leco 2000-FP, Leco Corp., St. Joseph, MI). Crude protein was calculated as N x 6.25. Dietary treatments (hay-fed and corn-fed) were maintained through mid-April; however, stockpiled orchardgrass ran out in mid-February, just prior to calving. Thus, performance, feed usage, and feed quality data were only reported for the period that ended just prior to calving. Cows calved between February 26 and April 19. Cows that were limit-fed corn calved in the drylot. Cows grazing stockpiled orchardgrass remained on pasture, where they calved and were supplemented with orchardgrass hay and corn until pasture began to grow in the spring. Cows fed hay calved on the 21-ha dormant pasture. Cows were weighed and condition-scored monthly from November to April. Intake was not restricted prior to weighing. Condition score ranged from 1 to 9, with 1 being thin and 9 being fat (NRC, 1996). Condition was scored by the same individual at each weighing. Calf birth weight was measured to determine whether gestation diet affected birth weight. Cows were exposed to bulls in June and July for a 45-d breeding season. Conception rates were determined by palpating cows in September to evaluate any residual effects of gestation diet on reproductive performance. Weight of calves was determined in mid-July to evaluate any residual effects of gestation diet the previous winter on subsequent calf performance.
Experiment 2
From January to April of 1999, 2000, and 2001, 24 mature, pregnant crossbred cows (initial BW = 677.7 ± 9.4 kg) per treatment from the Ohio Agricultural Technical Institute (ATI) were used to determine the efficacy of limit-fed corn, stockpiled orchardgrass, or ad libitum access to hay for maintaining cows in late gestation and early lactation. Hay was approximately 62.2% NDF and 14.1% CP. All cows grazed corn stalks from October to December prior to being allotted to treatments. Cows were randomly allotted to the three groups such that each group had a similar starting weight and age. Cows were reallotted to treatments and a small percentage were culled and replaced every year. Cows fed hay or limit-fed corn were treated as in Exp. 1, except cows fed hay remained on drylot, rather than on dormant pasture. Cows consuming stockpiled orchardgrass were treated as in Exp. 1, except that cows sequentially grazed 5 (yr 1) or 6 (yr 2 and 3) paddocks (21.7 ha total) ranging in size from 2.7 to 6.9 ha, and remained on pasture until late April. Feeds were sampled and analyzed for DM, CP, ADF, and NDF, and feed costs were determined according to the procedures described in Exp. 1. Dietary treatments were maintained until mid-April. Cows calved between February 8 and April 17. Cows fed hay and limit-fed corn calved on drylot, cows consuming stockpiled orchardgrass calved on pasture. Cows were weighed and condition scored as in experiment 1. Postcalving weight was taken within 1 wk after calving. At the termination of the trial, cows were placed on pasture for 5 d before a final weight was taken in order to equilibrate potential gut fill differences. Cows were synchronized and artificially inseminated, and conception rates were determined by ultrasound in late August. Weight of calves was determined in mid-August to evaluate any residual effects of lactation diet on subsequent calf performance.
Protocols concerning animal care followed guidelines recommended in the Guide for the Care and Use of Agricultural Animals in Agriculture Research and Teaching (FASS, 1999). Cow and calf performance was analyzed as a randomized complete block design using the GLM procedure of SAS (SAS Inst., Inc., Cary, NC). Treatment and block (yr) were the main effects and individual animals were used as the experimental units. No significant treatment x year interactions occurred, thus only main effect data will be presented. Relationships between time of season and nutrient composition (CP, ADF, and NDF percentage) and yield were analyzed using the REG procedures of SAS.
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Results |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionImplicationsLiterature Cited |
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One cow fed the hay-based diet died in yr 3 and was removed from the data set. Weight did not differ (P > 0.79) at the initiation of the trial or just prior to calving (Table 2). Cows on all treatments gained from 46 to 49 kg from November to February. Body condition score did not differ at the initiation of the trial (P > 0.93), but did differ (P < 0.01) when cows were last scored just prior to calving. Cows that were limit-fed corn carried the most condition; cows fed hay and cows consuming stockpiled orchardgrass carried less condition. Calving date and calf birth weight did not differ (P > 0.15) among treatments. After calving, cows limit-fed corn weighed the most (P < 0.10), followed by cows fed orchardgrass hay; cows consuming stockpiled orchardgrass weighed the least. Calves were weaned in July to be used for early-weaning experiments. Cow BW at weaning did not differ (P > 0.21) among treatments, but body condition did (P < 0.04). Cows limit-fed corn carried 4.9 to 5.9% more condition than cows fed hay, and cows grazing stockpiled orchardgrass, respectively. Calf weight at weaning did not differ (P > 0.22) due to diet during gestation. Diet during gestation did not affect (P > 0.18) conception rates.
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). Cows consuming stockpiled orchardgrass had to be fed harvested feed for 20 d due to inclement weather. During those 20 d, cows consumed 7.2 kg of DM/d, which, averaged over the entire 112 d of the trial, equaled 1.28 kg of DM/d. It cost almost twice as much to feed mid- to late-gestation cows a hay-based diet ad libitum compared to limit-feeding cows a grain-based diet, which is in agreement with results from Loerch (1996). Harvested feed costs were $0.13•cow-1•d-1 for cows consuming stockpiled orchardgrass, $0.84•cow-1•d-1 for cows limit-fed corn, and $1.61•cow-1•d-1 for cows fed a hay-based diet ad libitum. Cows grazing stockpiled orchardgrass grazed on 15.2 ha, resulting in 0.49 ha available per cow. At 2,975.1 kg of DM per hectare, cows had 13.02 kg of DM potentially available to consume per day. Pasture rental costs were determined using the alternative feed method (Langemeier, 1997), where monthly pasture rent per hectare = average starting weight per 454 kg of the animals x average price per 909 kg (ton) of good grass hay x pasture quality factor (fair to good native pasture = 0.37). Monthly pasture rental cost for Exp. 1 was approximately $43.13/ha (1.46 x $80.00 x 0.37), resulting in a daily pasture rental cost of $1.44/ha ($43.13•30 d-1•mo-1). With the stocking rate at 0.49 cows per hectare, the pasture rental cost per cow came to $0.71•cow-1•d-1 ($1.44•ha-1•d-1 x 0.49 cows•ha-1). Adding in cost of harvested feed, it cost $0.84•cow-1•d–1 to place cows on stockpiled orchardgrass during mid- to late gestation. Yield and CP content (P > 0.76) of pastures did not differ at different times of the year (Figure 1), but ADF and NDF content (P < 0.01) increased (r2 = 0.56 and 0.56, respectively) as the year went on, indicating that the orchardgrass became less digestible.
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If cows were found to be open, did not calve by the end of the 98 d trial, died, or experienced any other health problem (prolapse, lameness, Johnne’s disease), they were removed from the data set. Four cows were removed in yr 1 (1, 1, and 2 for cows fed corn, hay, and stockpiled orchardgrass, respectively), seven cows were removed in yr 2 (3, 1, and 3 for cows fed corn, hay, and stockpiled orchardgrass, respectively), and 11 cows were removed in yr 3 (3, 1, and 7 for cows fed corn, hay, and stockpiled orchardgrass, respectively). Performance data includes only cows that remained in the data set. Intake data were adjusted to account for cows that were removed and when they were removed. Weight and BCS did not differ (P > 0.17) at the initiation of the trial (Table 4). Cows fed the hay-based diet lost 8.9 kg, cows limit-fed a corn-based diet lost 27.0 kg, and cows fed stockpiled orchardgrass lost 45.5 kg from the initiation of the trial to calving (taken within 1 wk of calving). Thus, after calving weights were affected (P < 0.01) by diet. Cows fed the hay-based diet ad libitum were the heaviest after calving, cows limit-fed the corn-based diet had an intermediate postcalving weight, and cows fed stockpiled orchardgrass were the lightest after calving. Calf birth weight did not differ (P > 0.84), thus the difference in cow BW postcalving is primarily due to a reduction in the cow’s BW as a result of dietary treatment. Weight and body condition of cows did not differ (P > 0.38) at the end of the winter feeding period in April or in the following October. Calves were weaned in August, and weight did not differ (P > 0.36) among treatments. Diet during late gestation and early lactation did not affect (P > 0.12) conception rates.
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). During yr 3, all cows were fed melengesterol acetate (Pharmacia & Upjohn, Kalamazoo, MI) for 14 d in April to synchronize estrus. Cows on the hay based diet were fed melengesterol acetate with a corn carrier, thus when averaged over the 3 yr, cows fed the hay-based diet consumed an average of 0.08 kg of corn per cow each day. Cows consuming stockpiled orchardgrass had to be fed harvested feed for 12 d due to inclement weather. During those 12 d, stockpiled orchardgrass cows consumed 9.4 kg of harvested DM/d, which, averaged over the entire 98 d of the trial, equals 1.15 kg of harvested DM/d. It cost almost twice as much to feed late-gestation/early-lactation cows a hay-based diet ad libitum compared to limit-feeding cows a grain-based diet, which is in agreement with results from Loerch (1996). Harvested feed costs were $0.12•cow-1•d-1 for cows consuming stockpiled orchardgrass, $0.81•cow-1•d-1 for cows limit fed corn, and $1.64•cow-1•d-1 for cows fed a hay-based diet ad libitum. Feed costs were calculated using the same feed prices as in Exp. 1. Cows grazing on stockpiled orchardgrass grazed on 21.7 ha, resulting in 0.91 ha available per cow. At 2,361.2 kg of DM per hectare, cows had 21.8 kg of DM potentially available to consume per day. Pasture rental costs were determined using the alternative feed method (Langemeier, 1997), where monthly pasture rent per hectare = average starting weight per 454 kg of the animals x average price per 909 kg (ton) of good grass hay x pasture quality factor (fair to good native pasture = 0.37). Monthly pasture rental cost for Exp. 2 was approximately $43.81/ha (1.48 x $80.00 x 0.37), resulting in a daily pasture rental cost of $1.46/ha ($43.81 ÷ 30 d•mo-1). With the stocking rate at 0.91 cows per hectare, the pasture rental cost per cow came to $1.33•cow-1•d-1 ($1.46•ha-1•d-1 x 0.91 cows•ha-1). Adding in the cost of harvested feed, it cost $1.45•cow-1•d-1 to place cows on stockpiled orchardgrass during late gestation and early lactation. Yield, ADF, and NDF content did not differ (P > 0.25) at different times of the year, but CP content increased (P < 0.07) as the season progressed (Figure 2). As the year went on, CP content increased slightly, probably due to growth of new, higher quality pasture in early spring.
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionImplicationsLiterature Cited |
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Limit-feeding corn as an alternative to hay is a viable management option for gestating cows (Loerch, 1996). Ours is the first report to compare limit-fed corn and stockpiled forage in gestating and lactating cows. Supplementing hay-based diets with corn reduces forage utilization and digestible OM intake (Kartchner, 1980; Chase and Hibberd, 1987). However, limit feeding of corn-based diets avoids this negative associative effect because little forage is being fed. In the present trials, cows adjusted to the corn-based diet without problems. Limit-fed cows showed behavioral signs of being hungry, even though they had a caloric intake similar to that of cows fed hay ad libitum (approximately 14 Mcal of NEm per day); this is in agreement with Loerch (1996). Loerch (1996) also demonstrated that the breakeven price for hay was about $0.049/kg ($44.00/ton) when corn was priced at $0.079/kg ($2.00/bu). This means if hay cannot be produced or purchased for less than $0.049/kg, it is more economical to purchase corn for $0.079/kg and feed it on a limited basis.
Cost to feed stockpiled forage varies depending on the cow’s physiological stage of production. Feed offered for cows limit-fed corn can be manipulated to meet requirements for maintenance and growth as temperatures decline and as the fetus grows. For cows consuming stockpiled pasture, supplemental feed may need to be offered to adjust energy intake to meet requirements associated with growth of the fetus and lower temperatures. In both of these experiments, pasture intake was not supplemented, except when cows were unable to graze stockpiled forage. Based on the increased size of the fetus and lower temperatures, cows in late gestation and early lactation may have a greater demand for a supplement compared to cows in mid- to late gestation (NRC, 1996). In both experiments, the cows’ largest nutritional demand (calving and the start of lactation) occurred at a time when pasture quality was the lowest. Cows in Exp. 1 (mid- to late gestation) were removed from the experimental diets prior to calving. In Exp. 2, (late gestation and early lactation) cows remained on stockpiled orchardgrass through calving. The cost to graze cows on stockpiled orchardgrass was higher in Exp. 2 because less forage was available per hectare and more pasture area was needed to meet nutritional requirements for late gestation and early lactation. Hitz and Russell (1998) observed mean changes in in vitro organic matter disappearance, CP, NDF, and ADF concentrations during the winter grazing period were -0.09, -0.004, 0.10, and 0.11 percentage units/d, respectively, and did not differ between forage species or grazed and ungrazed areas. This indicates that the change was due to environmental conditions, not the presence of the cows. Hitz and Russell (1998) also demonstrated that the proportion of N as ADIN increased at a rate of 0.07% units of N/d throughout the year. In addition, mean ADIN concentration in grazed areas increased at a rate 0.05% units of N/d greater than those in ungrazed areas, suggesting that selection by grazing cattle for forage with greater quantities of available protein occurred.
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Implications |
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Footnotes |
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3 Present address: Univ. of Georgia, P.O. Box 1209, Tifton 31793.
Received for publication August 14, 2002. Accepted for publication November 15, 2002.
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Literature Cited |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionImplicationsLiterature Cited |
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