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Effects of cow-calf production system and postweaning management on calf performance
Applied Animal Science 35:66–73 https://doi.org/10.15232/aas.2018-01785 © 2019 American Registry of Professional Animal Scientists. All rights reserved.
ORIGINAL RESEARCH: Production and Management
Effects of cow-calf production system and postweaning management on calf performance S. E. Gardine,1 B. M. Boyd,1 PAS, C. J. Bittner,1 F. H. Hilscher,1 PAS, G. E. Erickson,1 PAS, K. H. Jenkins,2 PAS, T. J. Klopfenstein,1 PAS, and A. K. Watson,1* PAS 1 Department of Animal Science, University of Nebraska, Lincoln 68583; and 2Panhandle Research and Extension Center, University of Nebraska, Scottsbluff 69361
ABSTRACT A 3-yr study evaluated the effects of cow-calf production system and postweaning management on finishing performance and carcass characteristics of calves. Treatments were arranged as a 2 × 2 factorial (1 replication from each of 2 locations each year): (1) cow-calf production system: dry-lot feeding (DL) or grazing corn residue (GRZ) and (2) postweaning management: finishing (FIN) or growfinishing (GRW). From November to mid-April, DL pairs were fed a distillers and crop residue–based diet in pens and GRZ pairs were supplemented with distillers-based cubes while grazing corn residue. All calves were weaned in mid-April and received into the feedlot for postweaning management. In the FIN treatment, calves were directly adapted to a finishing diet following weaning. Calves in the GRW treatment were placed on a growing diet (30% Sweet Bran, 35% distillers grains, and 35% wheat straw) for 76 d before being adapted to the common finishing diet. Calves from GRZ had lighter BW entering the finishing phase than calves from DL (P < 0.01). However, there were no effects of cow-calf production system on final BW or HCW (P ≥ 0.15). Calves in the FIN treatment had greater ADG (P < 0.01) and improved G:F (P < 0.01). The GRW calves produced 35-kg-greater final BW (P < 0.01) and 23-kg-greater HCW (P < 0.01). Economics indicate that directly finishing calves resulted in similar net return (P = 0.16) because increased HCW offset the cost of 49 additional days in the feedlot for the GRW treatment. Key words: confinement feeding systems, cornstalk grazing, postweaning, feedlot
INTRODUCTION When traditional forage resources are limited, alternative beef production systems may be necessary. Research has demonstrated that year-round confinement of the cow
The authors declare no conflict of interest. *Corresponding author: awatson3@unl.edu
herd can be used as an alternative to traditional pasture cow-calf production (Warner et al., 2015). However, total confinement can be an expensive system. Within rural Nebraska, areas challenged by limited grassland tend to favor grain crop production. Consequently, a greater supply of corn residue is available for grazing. Research has demonstrated that production costs can be reduced by using corn residue grazing as a component of a semi-confined cow-calf production system (Gardine, 2018). However, data are limited on subsequent feedlot performance of calves produced from a confined cow-calf production system. In addition to alternative cow-calf production systems, different postweaning management strategies may be implemented. Two common postweaning systems are calffed and yearling systems. In calf-fed systems calves are directly adapted to a finishing diet following weaning, whereas in yearling systems there is a period of growth before the finishing phase. Calves are commonly grown in an extensive system using grazed forages or crop residue. An alternative growing program consists of backgrounding calves in pens in which harvested forages are fed. The type of postweaning management used can affect finishing performance and carcass characteristics. Research has indicated that calf-feds have improved feed efficiency, but yearlings gain faster and finish with greater BW (Griffin et al., 2007). There can also be carryover effects from preweaning management on postweaning performance or interactions between pre- and postweaning management (Funston et al., 2010; Rolfe, 2011; Rasby and Funston, 2016). The objective of the current study was to evaluate postweaning management from 2 intensively managed cow-calf production systems and determine the effects on finishing performance and carcass characteristics of steer and heifer calves.
MATERIALS AND METHODS All experimental facilities and management procedures were approved by the University of Nebraska–Lincoln Institutional Animal Care and Use Committee. Summerborn steer (n = 114) and heifer (n = 95) calves (initial BW
Postweaning calf performance
of 266 kg; SD = 42 kg) were used in a study conducted over 3 yr at the Eastern Nebraska Research and Extension Center feedlot. Calves were sourced from 2 cow herds maintained at either the Eastern Nebraska Research and Extension Center (124 calves) or the Panhandle Research and Extension Center (85 calves).
Cow-Calf Production System Within each location, cow herds were maintained in confinement from approximately April to November. Calves were born in the summer (mean calving date of July 15) while cows were in confinement. In November, cow-calf pairs were assigned randomly to 1 of 2 winter cow-calf production treatments: (1) dry-lot feeding (DL) or (2) corn residue grazing with supplementation (GRZ). Cow-calf pairs assigned to the DL treatment were limit fed a distillers and crop residue–based diet formulated to meet energy requirements of a lactating cow in early gestation. The diet was 80% TDN and provided 1.94 Mcal/kg of NEm. The amount of DM offered increased by 0.45 kg monthly to account for increasing intake of the growing calf. In yr 1 and 2, the amount of DM offered ranged from 11.6 to 13.4 kg/d. During yr 1 and 2, cows fed in the dry lot were gaining BW and BCS and were not at maintenance. To correct for the BW and BCS gain, the amount of DM offered to cows in the dry lot was reduced to a range of 11.1 to 12.9 kg/d during yr 3. Cow-calf pairs assigned to the GRZ treatment were hauled (less than 10 km) to irrigated cornstalk fields and supplemented with approximately 2.4 kg (range of 1.7 to 3.2 kg) of a distillers-based cube daily (93.28% dried distillers grains, 6.23% limestone, 0.21% pelleting binder, 0.11% vitamin A-D-E premix, 0.17% trace mineral premix). Calves from both cow-calf production systems were weaned in April and received into the Eastern Nebraska Research and Extension Center feedlot for postweaning treatments. The cow-calf production system and complete results of this portion of the system have been described by Gardine (2018).
Postweaning Management Once received into the feedlot, calves were allocated by previous location and winter cow-calf production treatment, stratified by initial BW, and assigned randomly within strata to 1 of 2 postweaning treatments (1 replication per location for each preweaning treatment over 3 yr for a total of 6 replications and 24 pens of cattle). The study was completely randomized with a 2 × 2 factorial treatment design. Factors were (1) cow-calf production system and (2) postweaning management. Cowcalf production treatments included winter DL or GRZ. Postweaning management treatments were a finish (FIN) or a grow-finish (GRW) treatment. Calves in the FIN treatment were directly adapted to a concentrate finishing diet (Table 1) following weaning. In the GRW treatment, calves were fed a growing diet (Table 1) for approximately 76 d before being adapted to the same finishing diet as
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calves in the FIN treatment. All calves (GRW and FIN) were adapted to the common finishing diet by decreasing the amount of wheat straw and distillers grains (DGS) in the diet while increasing the amount of high-moisture corn (HMC). Sweet Bran (Cargill Corn Milling, Blair, NE) was held constant at 30% of diet DM. Cattle were stepped up over 5 periods lasting a total of 28 d. The GRW diet was step 1 for the FIN treatment and was fed for 3 d. Step 2 included 15% HMC, 26% wheat straw, and 25% DGS and was fed for 5 d. Step 3 included 25% HMC, 21% wheat straw, and 20% DGS and was fed for 6 d. Step 4 included 35% HMC, 16% wheat straw, and 15% DGS and was fed for 7 d. Step 5 included 45% HMC, 9% wheat straw (grass hay in yr 2 and 3), and 12% DGS and was fed for 7 d. All feedstuffs were sampled weekly for laboratory analysis of DM (60°C forced-air oven for 48 h), CP (AOAC 990.03; AOAC International, 2006), and NDF (Van Soest and Marcus, 1964; Van Soest et al., 1991). At initial processing in yr 1, calves in both treatments were vaccinated against infectious bovine rhinotracheitis, bovine viral diarrhea (types 1 and 2), parainfluenza 3, and bovine respiratory syncytial virus (Bovi-Shield Gold 5, Zoetis, Florham Park, NJ); poured with an insecticide (StandGuard, Elanco Animal Health, Greenfield, IN); and implanted on d 1 with 200 mg of trenbolone acetate and 40 mg of estradiol (steers; Revalor XS, Merck Animal Health, Summit, NJ) or 80 mg of trenbolone acetate and 8 mg of estradiol (heifers; Revalor-IH, Merck Animal Health). Heifers were re-implanted with 200 mg of trenbolone acetate and 20 mg of estradiol (Revalor 200, Merck Animal Health) approximately 100 d before slaughter date. Calves in the FIN treatment began the finishing phase April 21 and were slaughtered November 4 (197 d on feed). A grower diet was fed to calves in the GRW treatment for 79 d. The GRW calves were then adapted to the common finishing diet (Table 1) and slaughtered on January 6 (181 d on feed). In yr 2 and 3, all calves were vaccinated against infectious bovine rhinotracheitis, bovine viral diarrhea (types 1 and 2), parainfluenza 3, and bovine respiratory syncytial virus (Titanium 5, Elanco Animal Health); poured with an insecticide (StandGuard, Elanco Animal Health); and implanted with 80 mg of trenbolone acetate and 16 mg of estradiol (steers; Component TE-IS, Elanco Animal Health) or 80 mg of trenbolone acetate and 8 mg of estradiol (heifers; Component TE-IH, Elanco Animal Health) at initial processing. All calves were then re-implanted with 200 mg of trenbolone acetate and 20 mg of estradiol (Component TE-200, Elanco Animal Health) approximately 100 d before slaughter. In yr 2, calves in the FIN treatment entered the finishing phase April 27 and were slaughtered November 2 (189 d on feed). The GRW calves were fed the grower diet for 73 d before adaptation to the common finishing diet. The GRW calves were slaughtered December 28 (166 d on feed). In yr 3, FIN calves began the finishing phase on April 21 and were slaughtered on November 7 (201 d on feed). Calves in the GRW treatment
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Table 1. Composition of growing and finishing diets (DM basis) Item Growing diet Ingredient, % Sweet Bran1 Wheat straw Modified distillers grains Wet distillers grains Supplement2 Fine ground corn Limestone Tallow Salt Trace mineral premix3 Vitamin A-D-E premix4 Nutrient composition,5 % CP NDF Fat Finishing diet Ingredient, % High-moisture corn Sweet Bran1 Wheat straw Grass hay Modified distillers grains Wet distillers grains Supplement6 Fine ground corn Limestone Tallow Salt Trace mineral premix3 Vitamin A-D-E premix4 Nutrient composition,5 % CP NDF Fat
Yr 1
Yr 2
Yr 3
30 31 35 — 4 1.535 2.0 0.10 0.30 0.05 0.015 19.2 41.3 5.6
30 31 — 35 4 1.535 2.0 0.10 0.30 0.05 0.015 19.8 42.3 5.8
30 31 — 35 4 1.535 2.0 0.10 0.30 0.05 0.015 19.8 42.3 5.8
50 30 5 — 10 — 5 2.82 1.715 0.10 0.30 0.05 0.015 15.1 20.0 4.7
51 30 — 5 10 — 4 1.82 1.715 0.10 0.30 0.05 0.015 15.3 19.6 4.7
51 30 — 5 — 10 4 1.82 1.715 0.10 0.30 0.05 0.015 15.4 19.9 4.7
Branded wet corn gluten feed (Cargill Corn Milling, Blair, NE). 2 Formulated to provide 200 mg/animal of monensin daily (Rumensin, Elanco Animal Health, Greenfield, IN). 3 Trace mineral premix contained 10% Mg, 6% Zn, 4.5% Fe, 2% Mn, 0.5% Cu, 0.3% I, and 0.05% Co. 4 Vitamin A-D-E premix contained 1,500 IU of vitamin A, 3,000 IU of vitamin D, and 3.7 IU of vitamin E per gram. 5 Nutrient analysis measured on weekly samples of dietary ingredients (CP and NDF). Fat content as reported by NASEM (2016). 6 Formulated to provide 330 mg/animal of monensin (Rumensin) and 90 mg/animal of tylosin daily (Tylan, Elanco Animal Health). 1
were fed the grower diet for 77 d before adaptation to the finishing diet. The GRW calves were then slaughtered on December 20 (160 d on feed). Ractopamine hydrochloride (Optaflexx; Elanco Animal Health) was included (300 mg/head daily) in the common finishing diet for the last 28 d on feed for all cattle every year. Weights were collected over 2 consecutive days at trial initiation. Before collecting weights, calves were limit fed a common diet for a minimum of 5 d to minimize gastrointestinal weight variation (Watson et al., 2013). For calves in the GRW treatment, ending BW for the growing phase was used as initial BW for the finishing phase. In yr 1, a 4% shrink was applied to calves in the GRW treatment upon completion of the growing phase due to calves not being limit fed before collecting weights on 2 consecutive days. In yr 2 and 3, GRW calves were limit fed between phases before collecting weights on 2 consecutive days. To obtain a common physiological endpoint between treatments, ultrasonography was used to detect 12th rib fat thickness on GRW cattle approximately 40 d before projected slaughter date each year. The ultrasound scans were then used to set slaughter date by targeting backfat thickness to be equal to FIN cattle. All cattle were slaughtered at Greater Omaha Packing Co. (Omaha, NE). On the day of slaughter, HCW and liver abscess scores were recorded. Following a 48-h chill, 12th rib fat thickness, marbling score, and LM area were recorded. Final BW, ADG, and G:F were calculated on a carcass-adjusted basis using a common DP of 63%. Yield grade was calculated using the following equation (USDA, 2016): 2.5 + (6.35 × 12th rib fat depth, cm) − (2.06 × LM area, cm2) + (0.2 × KPH, %) + (0.0017 × HCW, kg).
Economic Analysis A 10-yr (2007–2016) economic analysis was conducted to compare postweaning management systems. Data were collected from the time of weaning through slaughter. Days spent in each phase and performance data from the current study were used to determine costs, revenue, and net return on a dressed pricing basis. For initial purchase price, calf prices were collected from Schulz (2017) to determine 10-yr average purchase price for weaned calves (Table 2). To account for differences in weaning weights between cow-calf production systems, a price slide of $17.23/45 kg was used. The price slide was based on a regression of a 10-yr average price of steer and heifer calves weighing 226 to 272 kg and a 10-yr average price of steer and heifer calves weighing 272 to 318 kg. When calculating feed costs, all costs were calculated on a DM basis. Cash corn prices were collected from Johanns (2017) to determine a 10-yr average corn price of $0.18/kg ($4.59/25.45 kg). The costs of distillers grains and Sweet Bran were calculated as 100% of the value of corn (DM basis). Base price for grass hay and wheat straw was $50 per 907 kg. An additional $15 per 907 kg was charged to grass hay and wheat straw to account for grinding cost.
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Supplement was priced at $200 per 907 kg. Interest rates for agricultural operating loans were collected from the Federal Reserve Bank of Kansas City (2016). A 10-yr average interest rate of 6.2% was applied to the total operating cost associated with each phase and half of the initial animal cost. Feedlot yardage was held constant at $0.45 per head per day for all treatments. Similarly, all steers and heifers were charged $15 per head for health and processing fees. Actual morbidity of calves on each treatment was similar and minimal (12 animals treated in total); therefore, a standard fee of $15 was charged to all treatments. A 10-yr average live cattle price as reported by Schulz (2017) was adjusted to a 63% DP to determine selling price ($1.83/0.45 kg) on a dressed basis. Total revenue was calculated by multiplying dressed selling price by HCW. Total costs included initial purchase cost with interest plus operating costs associated with the growing or finishing phase or both. Net return was then determined by subtracting total costs from total revenue. Cost of gain (COG) in each phase was calculated by dividing costs associated with each phase (not including purchase price of the animal) by the BW gained during the phase.
Statistical Analysis Data were analyzed using the mixed procedure of SAS (SAS Institute Inc., Cary, NC) as a completely randomized design. Experimental unit was pen (24 total) with cow-calf production system, postweaning management, and the cow-calf × postweaning interaction included in the model as fixed effects. Location and year were included as random effects. Because the proportion of steers and heifers varied within pen, proportion of steers within each pen was included as a covariate for all variables.
RESULTS AND DISCUSSION Growing Phase Performance of GRW cattle during the growing phase is presented in Table 3. Initial BW was lighter for calves that had previously been wintered on cornstalks compared with calves wintered in the dry lot (P = 0.02). However, GRZ calves had greater ADG (P = 0.03) and tended to have greater DMI (P = 0.09) and improved feed efficiency (P = 0.07) compared with DL calves. There was a 33-kg difference in initial BW and a 21-kg difference in ending BW for the growing period; therefore, the GRZ cattle compensated by 12 kg (36%). Compensatory growth is a period of nutrient (typically energy or protein) restriction followed by a period of relatively fast growth (NASEM, 2016). The response is due to a combination of factors including increased efficiency and energy utilization, decreased organ mass, and increased intake (Fox et al., 1972; Horton and Holmes, 1978; Sainz and Bentley, 1997). Compensatory growth has been reported for calves grazing summer grass following
Table 2. Economic assumptions applied to postweaning management systems1 Item Growing phase Yardage, $/animal daily Diet cost, $/907 kg Interest, % Finishing phase Yardage, $/animal daily Health and processing, $/animal Diet cost, $/907 kg Interest, % Cattle prices Feeder calf price,2 $/0.45 kg Feeder calf price,3 $/0.45 kg Selling price carcass basis,4 $/0.45 kg Interest, %
FIN
— — —
GRW
0.45 15.00 188.15 6.2 1.53 1.36 1.83
0.45 156.49 6.2 0.45 15.00 188.15 6.2 1.53 1.36 1.83
6.2
6.2
FIN = calves directly adapted to finishing diet following weaning; GRW = calves fed grower-ration diet for 76 d before finishing phase. 2 The 10-yr average calf price for steers and heifers weighing 226 to 273 kg. 3 The 10-yr average calf price for steers and heifers weighing 272 to 318 kg. 4 The 10-yr average live cattle price adjusted to a 63% DP for calculation of selling price on a carcass basis. 1
corn residue grazing during the winter (Gillespie-Lewis et al., 2015). Compensation by cattle grazing grass following nutrient restriction during the winter has been reported to range from 19 to 88% (Klopfenstein et al., 2000). However in all of these studies, treatments were applied to weaned instead of nursing calves. In the current study, compensatory growth by GRZ calves was likely due to both increased DMI and efficiency and did carry over into the finishing phase.
Finishing Phase No significant cow-calf production by postweaning management interactions were observed for any finishing performance variables tested (P ≥ 0.15; Table 3). Cattle that were previously wintered on cornstalks had lighter initial BW entering the finishing phase than cattle that had been wintered in the dry lot (P < 0.01). However, GRZ cattle had a compensatory response characterized by greater (P ≤ 0.02) ADG and G:F and a tendency (P = 0.08) for greater DMI during finishing compared with DL cattle. Previous research has also reported that cattle have increased DMI (Mader et al., 1989; Sainz et al., 1995) and compensatory gain (Carstens et al., 1991; Sainz et al., 1995; Neel et al., 2007) following a period of growth restriction.
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Table 3. Effects of postweaning management and cow-calf production system on finishing performance and carcass characteristics1 FIN Item Growing performance Days on feed Initial BW, kg Ending BW, kg DMI, kg/d ADG, kg G:F Finishing performance Days on feed Initial BW, kg Final BW,3 kg DMI, kg/d ADG, kg G:F Carcass characteristics HCW, kg LM area, cm2 12th rib fat, cm Marbling4 Calculated YG
DL
— — — — — 196 279 594 9.4 1.61 0.172 374 87.7 1.40 424a 3.3
GRW GRZ
DL
— — — — — 196 251 589 9.6 1.73 0.180 371 89.0 1.32 422a 3.1
76 284 377 7.9 1.22 0.155 169 377 631 9.9 1.48 0.150 399 89.7 1.52 438a 3.4
P-value GRZ
SEM
76 251 8 356 8 8.3 0.5 1.37 0.054 0.167 0.019 169 356 10 621 15 10.3 0.4 1.58 0.044 0.152 0.004 391 10 88.4 1.9 1.52 0.14 491b 15 3.4 0.2
Postweaning
— — — — — <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 0.66 0.06 <0.01 0.04
Cow-calf
0.02 0.11 0.09 0.03 0.07 <0.01 0.15 0.08 <0.01 0.02 0.15 0.92 0.65 0.05 0.44
Int.2
— — — — — 0.62 0.65 0.60 0.80 0.15 0.64 0.15 0.65 0.04 0.33
FIN = calves directly adapted to finishing diet following weaning; GRW = calves fed grower-ration diet for 76 d before finishing phase; DL = winter dry-lot feeding of cow-calf pair before weaning; GRZ = winter corn-residue grazing of cow-calf pair before weaning. 2 Test for cow-calf production by postweaning management interaction. 3 Calculated on a carcass-adjusted basis using a common DP of 63%. 4 Marbling score: 400 = small, 500 = modest, and so on. 1
When evaluating the effects of postweaning management on finishing performance, GRW cattle had greater initial BW, final BW, and DMI compared with FIN cattle (P < 0.01). However, cattle in the FIN treatment had increased ADG and subsequently improved G:F compared with GRW cattle (P < 0.01). Although results from the current study are generally consistent with previous data evaluating calf-feds and yearlings, the age of calves used in the current study varied from typical calf-feds and yearlings. The GRW and FIN cattle were almost 9 mo old at the onset of postweaning treatments. Consequently, FIN cattle were older than typical calf-feds at feedlot placement. However, GRW cattle were similar in age (12 mo) to short-yearlings upon entering the finishing phase. Previous data suggest that calf-feds have lower DMI, similar ADG, and improved feed efficiency compared with short-yearlings (Adams et al., 2010). Although the responses observed for DMI and G:F of the FIN and GRW cattle are similar to that of calffeds and yearlings, daily gain during finishing was greater for FIN cattle compared with GRW cattle. The relatively fast rate of gain during the 76-d growing period may have influenced subsequent finishing daily gain of GRW cattle.
Lancaster et al. (2014) observed that stocker-phase ADG was inversely related to finishing ADG and G:F, indicating that greater rate of gain during the stocker phase is followed by slower rate of gain and worsened feed efficiency during the finishing phase. Initial finishing BW may also affect ADG during finishing. Initial finishing BW of GRW cattle was almost 100 kg heavier than initial BW of FIN cattle. Similar to the responses observed in the current study, Reinhardt et al. (2009) observed that finishing ADG declined as initial finishing BW increased. In contrast, other researchers have reported that BW at the onset of finishing is positively related to finishing ADG (Reuter and Beck, 2013; Bittner, 2016). Furthermore, Reuter and Beck (2013) reported that initial finishing BW is a more powerful predictor than stocker ADG when predicting finishing performance. Differences in cattle (genetics, age, BW) as well as feed quality and quantity during both the growing and finishing periods may explain some of these differences. Furthermore, as discussed by Reuter and Beck (2013), BW at time of feedlot entry is confounded with season, previous ADG, and length of the growing period. Length and severity of nutrient restriction affect a calf’s ability to compensate
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(Fox et al., 1972). Calves in the current study on the GRZ treatment would have had minimal nutrient restrictions, although it is difficult to model because intake and forage quality measurements always contain some assumptions in grazing situations.
Carcass Characteristics A significant postweaning management effect was observed for HCW, with cattle in the GRW treatment producing 23-kg-greater carcass weight than FIN cattle (P < 0.01; Table 3). Twelfth rib fat thickness tended to be greater for GRW cattle relative to FIN cattle (P = 0.06). A significant postweaning management by cow-calf production interaction was observed for marbling (P = 0.04). Cattle in the GRW-GRZ treatment had greater marbling compared with cattle in the GRW-DL, FIN-DL, or FINGRZ treatments, which were not different from each other. A postweaning management effect was also observed for calculated YG, with GRW cattle having greater YG than FIN cattle (P = 0.04); however, the biological significance of this is unclear.
The increase in HCW of GRW cattle is in agreement with Adams et al. (2010), who observed a 37-kg increase in HCW for short-yearlings compared with calf-feds. In that study, short-yearlings and calf-feds were slaughtered at similar 12th rib fat thickness. Klopfenstein et al. (2000) illustrated the importance of comparing cattle at equal fat endpoints, especially when cattle are fed in different feeding programs. Bruns et al. (2004) reported that increased DOF resulted in increased HCW, fat thickness, and marbling. Because equal 12th rib fat thickness was not obtained between treatments in the current study, it is difficult to determine whether the difference in performance between the 2 postweaning systems was due to treatment or from feeding the GRW cattle to the point in which 12th rib fat thickness was increased. Because GRW cattle were slaughtered at greater fat thickness, it is interesting that marbling of GRW-DL cattle did not increase to the same degree as marbling of GRW-GRZ cattle. This suggests that marbling can be affected by nutrition before the finishing phase (Pethick et al., 2004). However, it is difficult to draw strong conclusions from marbling data with
Table 4. Economic analysis of cattle by postweaning management and cow-calf production system1 FIN Item Growing phase Purchase cost3,4 Diet cost3 Yardage cost3 Interest cost3 Growing COG5 Finishing phase Purchase cost3,4 Diet cost3 Yardage cost3 Interest cost3 Health and processing cost3 Finishing COG5 System (growing + finishing) Total revenue3,6 Total operating cost3 Total COG5 Net return3,7
DL
— — — — — 891.72 379.61 88.05 30.87 15.00 71.81 1,502.61 513.53 71.81 97.11
GRW GRZ
— — — — — 834.44 388.32 88.00 30.19 15.00 68.28 1,488.49 521.54 68.28 132.04
DL
P-value GRZ
SEM
Postweaning Cow-calf
894.80 835.70 15.34 — 104.94 109.24 8.58 — 34.35 34.35 — — 7.63 7.30 0.28 — 70.14 63.63 7.33 — — — — 14.8 — 351.06 360.63 19.19 <0.01 76.24 75.90 1.81 <0.01 25.64 24.95 1.21 <0.01 15.00 15.00 — — 81.82 79.46 1.71 <0.01 1,585.23 1,578.89 36.86 <0.01 614.86 627.36 26.78 <0.01 77.93 74.39 2.27 <0.01 76.12 116.27 18.35 0.16
0.04 0.17 — 0.11 0.12 0.01 0.14 0.86 0.24 — 0.01 0.46 0.30 0.01 0.01
Int.2
— — — — — — — 0.94 0.90 0.99 — 0.53 0.77 0.82 0.99 0.84
FIN = calves directly adapted to finishing diet following weaning; GRW = calves fed grower-ration diet for 76 d before finishing phase; DL = winter dry-lot feeding of cow-calf pair before weaning; GRZ = winter corn-residue grazing of cow-calf pair before weaning. 2 Test for cow-calf production by postweaning management interaction. 3 Variables presented as $ per animal. 4 Calculated by multiplying BW by 10-yr average steer and heifer price in 45.4-kg weight groups. 5 Cost of gain (COG; $/45 kg) calculated by dividing costs associated with each phase (animal purchase cost and interest on the animal not included) by the BW gained during the respective phase. 6 Calculated by multiplying HCW by dressed selling price. 7 Total revenue − (total operating cost + purchase cost). 1
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limited numbers (Owens and Gardner, 2000), and genetics can overshadow nutrition effects on marbling (Hocquette et al., 2010; Moisá et al., 2014).
Economic Analysis No significant cow-calf production by postweaning management interactions were observed for any economic variables tested (P ≥ 0.53; Table 4). Due to differences in initial BW, initial purchase cost during the growing phase was greater if calves had previously been wintered in the dry lot compared with calves wintered on cornstalks (P = 0.04; Table 4). There were no significant differences between treatments for growing costs (P ≥ 0.11) or growing COG (P = 0.12). Growing COG was numerically lower for GRZ calves as a result of greater daily gain during the growing phase. Likewise, initial purchase cost and COG during the finishing phase were greater for DL calves compared with GRZ calves (P = 0.01; Table 4). When evaluating the main effects of postweaning management on finishing variables, finishing costs were greater (P < 0.01) for FIN cattle compared with GRW cattle, largely due to FIN cattle having 27 more DOF during the finishing phase. Conversely, finishing COG was less (P < 0.01) for FIN cattle compared with GRW cattle due to FIN cattle having improved feed efficiency during finishing. For the economics of the weaning through slaughter portion of the system, GRZ cattle had less overall COG (P = 0.01; Table 4), which was a reflection of the improved feed efficiency observed for GRZ cattle relative to DL cattle. Although similar revenue (P = 0.46) was generated between treatments, GRZ cattle produced $38 greater net return than DL cattle (P = 0.01) as a result of reduced initial purchase cost of GRZ cattle. Because of increased HCW, GRW cattle generated $86 greater total revenue in relation to revenue received from FIN cattle (P < 0.01). However, FIN cattle had decreased total operating cost and COG (P < 0.01). Net return was $18 greater for FIN cattle but not statistically different between FIN and GRW cattle (P = 0.16). In the current analysis, the growing diet was 83% the cost of the finishing diet ($156/907 kg ÷ $188/907 kg). In order for net return to be equal between the GRW and FIN treatments, the cost of the growing diet would need to be 70% ($132 per 907 kg) of the cost of the finishing diet.
APPLICATIONS Calves wintered on cornstalks alongside their dams consistently responded with compensatory growth during the feedlot growing and finishing phases. Cattle wintered on cornstalks weighed less at the onset of postweaning treatments compared with cattle that had been wintered in the drylot. However, HCW was similar between treatments. Using a relatively rapid growing phase (76 d) on cattle before the finishing phase produced greater HCW and
generated more revenue compared with cattle directly adapted to a finishing diet following weaning. However, improved feed efficiency and greater daily gain of cattle directly adapted to the finishing diet resulted in similar net return relative to cattle fed a grower diet before being finished. Wintering lactating cow-calf pairs on corn residue is an economical option in Nebraska. Growing calves before the feedlot phase results in greater HCW but not always improved net return.
ACKNOWLEDGMENTS Funding was provided by the Dr. Kenneth and Caroline Eng Foundation.
LITERATURE CITED Adams, D. R., T. J. Klopfenstein, G. E. Erickson, W. A. Griffin, M. K. Luebbe, and J. R. Benton. 2010. Effects of sorting steers by body weight into calf-fed, summer yearling, and fall yearling feeding systems. Prof. Anim. Sci. 26:587–594. AOAC International. 2006. Official Method of Analysis. 18th ed. AOAC Int., Gaithersburg, MD. Bittner, C. J. 2016. Effects of feed additives and body weight on growth performance and carcass characteristics of beef finishing cattle. PhD Dissertation. Univ. of Nebraska, Lincoln. Bruns, K. W., R. H. Pritchard, and D. L. Boggs. 2004. The relationships among body weight, body composition, and intramuscular fat content in steers. J. Anim. Sci. 82:1315–1322. Carstens, G. E., D. E. Johnson, M. A. Ellenberger, and J. D. Tatum. 1991. Physical and chemical components of the empty body during compensatory growth in beef steers. J. Anim. Sci. 69:3251–3264. Federal Reserve Bank of Kansas City. 2016. 2007–2016. Agricultural Interest Rates. Accessed Mar. 5, 2018. http://www.kansascityfed.org/ research/indicatorsdata/agcreditsurvey. Fox, D. G., R. R. Johnson, R. L. Preston, T. R. Dockerty, and E. W. Klosterman. 1972. Protein and energy utilization during compensatory growth in beef cattle. J. Anim. Sci. 34:310–318. Funston, R. N., D. M. Larson, and K. A. Vonnahme. 2010. Effects of maternal nutrition on conceptus growth and offspring performance: Implications for beef cattle production. J. Anim. Sci. 88:E205–E215. Gardine, S. E. 2018. Corn residue grazing as a component of semiconfined cow-calf production and the effects of post-weaning management on feedlot performance. MS Thesis. Univ. of Nebraska, Lincoln. Gillespie-Lewis, K. L., A. K. Watson, T. J. Klopfenstein, and J. C. MacDonald. 2015. Effect of winter supplementation level on yearlingsystem profitability. Prof. Anim. Sci. 31:448–454. Griffin, W. A., T. J. Klopfenstein, G. E. Erickson, D. M. Feuz, J. C. MacDonald, and D. J. Jordon. 2007. Comparison of performance and economics of a long-yearling and calf-fed system. Prof. Anim. Sci. 23:490–499. Hocquette, J. F., F. Gondret, E. Baéza, F. Médale, C. Jurie, and D. W. Pethick. 2010. Intramuscular fat content in meat-producing animals: Development, genetic and nutritional control, and identification of putative markers. Animal 4:303–319. Horton, G. M. J., and W. Holmes. 1978. Compensatory gain by beef cattle at grassland or on an alfalfa-based diet. J. Anim. Sci. 46:297– 303.
Postweaning calf performance Johanns, A. M. 2017. Iowa cash corn and soybean prices. Ag Decision Maker File A2–11. Iowa State Univ., Ames, IA. Klopfenstein, T., R. Cooper, D. J. Jordon, D. Shain, T. Milton, C. Calkins, and C. Rossi. 2000. Effects of backgrounding and growing programs on beef carcass quality and yield. J. Anim. Sci. 77:1–11. Lancaster, P. A., C. R. Krehbiel, and G. W. Horn. 2014. A metaanalysis of effects of nutrition and management during the stocker and backgrounding phase on subsequent finishing performance and carcass characteristics. Prof. Anim. Sci. 30:602–612. Mader, T. L., O. A. Turgeon Jr., T. J. Klopfenstein, D. R. Brink, and R. R. Oltjen. 1989. Effects of previous nutrition, feedlot regimen and protein level on feedlot performance of beef cattle. J. Anim. Sci. 67:318–328. Moisá, S. J., D. W. Shike, D. B. Faulkner, W. T. Meteer, D. Keisler, and J. J. Loor. 2014. Central role of the PPARγ gene network in coordinating beef cattle intramuscular adipogenesis in response to weaning age and nutrition. Gene Regul. Syst. Bio. 8:17–32. NASEM. (National Academies of Sciences, Engineering, and Medicine). 2016. Nutrient Requirements of Beef Cattle. 8th rev. ed. Natl. Acad. Press, Washington, DC. https://doi.org/10.17226/19014.
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Reinhardt, C. D., W. D. Busby, and L. R. Corah. 2009. Relationship of various incoming cattle traits with feedlot performance and carcass traits. J. Anim. Sci. 87:3030–3042. Reuter, R. R., and P. A. Beck. 2013. Southern section interdisciplinary beef cattle symposium. Carryover effects of stocker cattle systems on feedlot performance and carcass characteristics. J. Anim. Sci. 91:508–515. Rolfe, K. 2011. Supplementing distillers grains in extensive beef cattle systems. PhD Diss. Univ. Nebraska, Lincoln. Sainz, R. D., and B. E. Bentley. 1997. Visceral organ mass and cellularity in growth-restricted and refed beef steers. J. Anim. Sci. 75:1229–1236. Sainz, R. D., F. De la Torre, and J. W. Oltjen. 1995. Compensatory growth and carcass quality in growth-restricted and refed beef steers. J. Anim. Sci. 73:2971–2979. Schulz, L. 2017. Historic cattle prices. Ag Decision Maker File B2–12. Iowa State Univ., Ames, IA. USDA. 2016. United States Standards for Grades of Carcass Beef. Agric. Market. Serv., USDA, Washington, DC.
Neel, J. P. S., J. P. Fontenot, W. M. Clapham, S. K. Duckett, E. E. D. Felton, G. Scaglia, and W. B. Bryan. 2007. Effects of winter stocker growth rate and finishing system on: I. Animal performance and carcass characteristics. J. Anim. Sci. 85:2012–2018.
Van Soest, P. J., and W. C. Marcus. 1964. Methods for the determination of cell wall constituents in forages using detergents and the relationship between this fraction and voluntary intake and digestibility. J. Dairy Sci. 47:704 (Abstr.).
Owens, F. N., and B. A. Gardner. 2000. A review of the impact of feedlot management and nutrition on carcass measurements of feedlot cattle. J. Anim. Sci. 77:7–18.
Van Soest, P. J., J. B. Robertson, and B. A. Lewis. 1991. Methods for dietary fiber, neutral detergent fiber, and non-starch polysaccharides in relation to animal nutrition. J. Dairy Sci. 74:3583–3597.
Pethick, D. W., G. S. Harper, and V. H. Oddy. 2004. Growth, development and nutritional manipulation of marbling in cattle: A review. Aust. J. Exp. Agric. 44:705–715.
Warner, J. M., K. H. Jenkins, R. J. Rasby, M. K. Luebbe, G. E. Erickson, and T. J. Klopfenstein. 2015. The effect of calf age at weaning on cow and calf performance and feed utilization by cow-calf pairs. Prof. Anim. Sci. 31:455–461.
Rasby, R. J., and R. N. Funston. 2016. Invited Review: Nutrition and management of cows: Supplementation and feed additives. Prof. Anim. Sci. 32:135–144.
Watson, A. K., B. L. Nuttelman, T. J. Klopfenstein, L. W. Lomas, and G. E. Erickson. 2013. Impacts of a limit-feeding procedure on variation and accuracy of cattle weights. J. Anim. Sci. 91:5507–5517.
ORIGINAL RESEARCH: Production and Management
Effects of cow-calf production system and postweaning management on calf performance S. E. Gardine,1 B. M. Boyd,1 PAS, C. J. Bittner,1 F. H. Hilscher,1 PAS, G. E. Erickson,1 PAS, K. H. Jenkins,2 PAS, T. J. Klopfenstein,1 PAS, and A. K. Watson,1* PAS 1 Department of Animal Science, University of Nebraska, Lincoln 68583; and 2Panhandle Research and Extension Center, University of Nebraska, Scottsbluff 69361
ABSTRACT A 3-yr study evaluated the effects of cow-calf production system and postweaning management on finishing performance and carcass characteristics of calves. Treatments were arranged as a 2 × 2 factorial (1 replication from each of 2 locations each year): (1) cow-calf production system: dry-lot feeding (DL) or grazing corn residue (GRZ) and (2) postweaning management: finishing (FIN) or growfinishing (GRW). From November to mid-April, DL pairs were fed a distillers and crop residue–based diet in pens and GRZ pairs were supplemented with distillers-based cubes while grazing corn residue. All calves were weaned in mid-April and received into the feedlot for postweaning management. In the FIN treatment, calves were directly adapted to a finishing diet following weaning. Calves in the GRW treatment were placed on a growing diet (30% Sweet Bran, 35% distillers grains, and 35% wheat straw) for 76 d before being adapted to the common finishing diet. Calves from GRZ had lighter BW entering the finishing phase than calves from DL (P < 0.01). However, there were no effects of cow-calf production system on final BW or HCW (P ≥ 0.15). Calves in the FIN treatment had greater ADG (P < 0.01) and improved G:F (P < 0.01). The GRW calves produced 35-kg-greater final BW (P < 0.01) and 23-kg-greater HCW (P < 0.01). Economics indicate that directly finishing calves resulted in similar net return (P = 0.16) because increased HCW offset the cost of 49 additional days in the feedlot for the GRW treatment. Key words: confinement feeding systems, cornstalk grazing, postweaning, feedlot
INTRODUCTION When traditional forage resources are limited, alternative beef production systems may be necessary. Research has demonstrated that year-round confinement of the cow
The authors declare no conflict of interest. *Corresponding author: awatson3@unl.edu
herd can be used as an alternative to traditional pasture cow-calf production (Warner et al., 2015). However, total confinement can be an expensive system. Within rural Nebraska, areas challenged by limited grassland tend to favor grain crop production. Consequently, a greater supply of corn residue is available for grazing. Research has demonstrated that production costs can be reduced by using corn residue grazing as a component of a semi-confined cow-calf production system (Gardine, 2018). However, data are limited on subsequent feedlot performance of calves produced from a confined cow-calf production system. In addition to alternative cow-calf production systems, different postweaning management strategies may be implemented. Two common postweaning systems are calffed and yearling systems. In calf-fed systems calves are directly adapted to a finishing diet following weaning, whereas in yearling systems there is a period of growth before the finishing phase. Calves are commonly grown in an extensive system using grazed forages or crop residue. An alternative growing program consists of backgrounding calves in pens in which harvested forages are fed. The type of postweaning management used can affect finishing performance and carcass characteristics. Research has indicated that calf-feds have improved feed efficiency, but yearlings gain faster and finish with greater BW (Griffin et al., 2007). There can also be carryover effects from preweaning management on postweaning performance or interactions between pre- and postweaning management (Funston et al., 2010; Rolfe, 2011; Rasby and Funston, 2016). The objective of the current study was to evaluate postweaning management from 2 intensively managed cow-calf production systems and determine the effects on finishing performance and carcass characteristics of steer and heifer calves.
MATERIALS AND METHODS All experimental facilities and management procedures were approved by the University of Nebraska–Lincoln Institutional Animal Care and Use Committee. Summerborn steer (n = 114) and heifer (n = 95) calves (initial BW
Postweaning calf performance
of 266 kg; SD = 42 kg) were used in a study conducted over 3 yr at the Eastern Nebraska Research and Extension Center feedlot. Calves were sourced from 2 cow herds maintained at either the Eastern Nebraska Research and Extension Center (124 calves) or the Panhandle Research and Extension Center (85 calves).
Cow-Calf Production System Within each location, cow herds were maintained in confinement from approximately April to November. Calves were born in the summer (mean calving date of July 15) while cows were in confinement. In November, cow-calf pairs were assigned randomly to 1 of 2 winter cow-calf production treatments: (1) dry-lot feeding (DL) or (2) corn residue grazing with supplementation (GRZ). Cow-calf pairs assigned to the DL treatment were limit fed a distillers and crop residue–based diet formulated to meet energy requirements of a lactating cow in early gestation. The diet was 80% TDN and provided 1.94 Mcal/kg of NEm. The amount of DM offered increased by 0.45 kg monthly to account for increasing intake of the growing calf. In yr 1 and 2, the amount of DM offered ranged from 11.6 to 13.4 kg/d. During yr 1 and 2, cows fed in the dry lot were gaining BW and BCS and were not at maintenance. To correct for the BW and BCS gain, the amount of DM offered to cows in the dry lot was reduced to a range of 11.1 to 12.9 kg/d during yr 3. Cow-calf pairs assigned to the GRZ treatment were hauled (less than 10 km) to irrigated cornstalk fields and supplemented with approximately 2.4 kg (range of 1.7 to 3.2 kg) of a distillers-based cube daily (93.28% dried distillers grains, 6.23% limestone, 0.21% pelleting binder, 0.11% vitamin A-D-E premix, 0.17% trace mineral premix). Calves from both cow-calf production systems were weaned in April and received into the Eastern Nebraska Research and Extension Center feedlot for postweaning treatments. The cow-calf production system and complete results of this portion of the system have been described by Gardine (2018).
Postweaning Management Once received into the feedlot, calves were allocated by previous location and winter cow-calf production treatment, stratified by initial BW, and assigned randomly within strata to 1 of 2 postweaning treatments (1 replication per location for each preweaning treatment over 3 yr for a total of 6 replications and 24 pens of cattle). The study was completely randomized with a 2 × 2 factorial treatment design. Factors were (1) cow-calf production system and (2) postweaning management. Cowcalf production treatments included winter DL or GRZ. Postweaning management treatments were a finish (FIN) or a grow-finish (GRW) treatment. Calves in the FIN treatment were directly adapted to a concentrate finishing diet (Table 1) following weaning. In the GRW treatment, calves were fed a growing diet (Table 1) for approximately 76 d before being adapted to the same finishing diet as
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calves in the FIN treatment. All calves (GRW and FIN) were adapted to the common finishing diet by decreasing the amount of wheat straw and distillers grains (DGS) in the diet while increasing the amount of high-moisture corn (HMC). Sweet Bran (Cargill Corn Milling, Blair, NE) was held constant at 30% of diet DM. Cattle were stepped up over 5 periods lasting a total of 28 d. The GRW diet was step 1 for the FIN treatment and was fed for 3 d. Step 2 included 15% HMC, 26% wheat straw, and 25% DGS and was fed for 5 d. Step 3 included 25% HMC, 21% wheat straw, and 20% DGS and was fed for 6 d. Step 4 included 35% HMC, 16% wheat straw, and 15% DGS and was fed for 7 d. Step 5 included 45% HMC, 9% wheat straw (grass hay in yr 2 and 3), and 12% DGS and was fed for 7 d. All feedstuffs were sampled weekly for laboratory analysis of DM (60°C forced-air oven for 48 h), CP (AOAC 990.03; AOAC International, 2006), and NDF (Van Soest and Marcus, 1964; Van Soest et al., 1991). At initial processing in yr 1, calves in both treatments were vaccinated against infectious bovine rhinotracheitis, bovine viral diarrhea (types 1 and 2), parainfluenza 3, and bovine respiratory syncytial virus (Bovi-Shield Gold 5, Zoetis, Florham Park, NJ); poured with an insecticide (StandGuard, Elanco Animal Health, Greenfield, IN); and implanted on d 1 with 200 mg of trenbolone acetate and 40 mg of estradiol (steers; Revalor XS, Merck Animal Health, Summit, NJ) or 80 mg of trenbolone acetate and 8 mg of estradiol (heifers; Revalor-IH, Merck Animal Health). Heifers were re-implanted with 200 mg of trenbolone acetate and 20 mg of estradiol (Revalor 200, Merck Animal Health) approximately 100 d before slaughter date. Calves in the FIN treatment began the finishing phase April 21 and were slaughtered November 4 (197 d on feed). A grower diet was fed to calves in the GRW treatment for 79 d. The GRW calves were then adapted to the common finishing diet (Table 1) and slaughtered on January 6 (181 d on feed). In yr 2 and 3, all calves were vaccinated against infectious bovine rhinotracheitis, bovine viral diarrhea (types 1 and 2), parainfluenza 3, and bovine respiratory syncytial virus (Titanium 5, Elanco Animal Health); poured with an insecticide (StandGuard, Elanco Animal Health); and implanted with 80 mg of trenbolone acetate and 16 mg of estradiol (steers; Component TE-IS, Elanco Animal Health) or 80 mg of trenbolone acetate and 8 mg of estradiol (heifers; Component TE-IH, Elanco Animal Health) at initial processing. All calves were then re-implanted with 200 mg of trenbolone acetate and 20 mg of estradiol (Component TE-200, Elanco Animal Health) approximately 100 d before slaughter. In yr 2, calves in the FIN treatment entered the finishing phase April 27 and were slaughtered November 2 (189 d on feed). The GRW calves were fed the grower diet for 73 d before adaptation to the common finishing diet. The GRW calves were slaughtered December 28 (166 d on feed). In yr 3, FIN calves began the finishing phase on April 21 and were slaughtered on November 7 (201 d on feed). Calves in the GRW treatment
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Table 1. Composition of growing and finishing diets (DM basis) Item Growing diet Ingredient, % Sweet Bran1 Wheat straw Modified distillers grains Wet distillers grains Supplement2 Fine ground corn Limestone Tallow Salt Trace mineral premix3 Vitamin A-D-E premix4 Nutrient composition,5 % CP NDF Fat Finishing diet Ingredient, % High-moisture corn Sweet Bran1 Wheat straw Grass hay Modified distillers grains Wet distillers grains Supplement6 Fine ground corn Limestone Tallow Salt Trace mineral premix3 Vitamin A-D-E premix4 Nutrient composition,5 % CP NDF Fat
Yr 1
Yr 2
Yr 3
30 31 35 — 4 1.535 2.0 0.10 0.30 0.05 0.015 19.2 41.3 5.6
30 31 — 35 4 1.535 2.0 0.10 0.30 0.05 0.015 19.8 42.3 5.8
30 31 — 35 4 1.535 2.0 0.10 0.30 0.05 0.015 19.8 42.3 5.8
50 30 5 — 10 — 5 2.82 1.715 0.10 0.30 0.05 0.015 15.1 20.0 4.7
51 30 — 5 10 — 4 1.82 1.715 0.10 0.30 0.05 0.015 15.3 19.6 4.7
51 30 — 5 — 10 4 1.82 1.715 0.10 0.30 0.05 0.015 15.4 19.9 4.7
Branded wet corn gluten feed (Cargill Corn Milling, Blair, NE). 2 Formulated to provide 200 mg/animal of monensin daily (Rumensin, Elanco Animal Health, Greenfield, IN). 3 Trace mineral premix contained 10% Mg, 6% Zn, 4.5% Fe, 2% Mn, 0.5% Cu, 0.3% I, and 0.05% Co. 4 Vitamin A-D-E premix contained 1,500 IU of vitamin A, 3,000 IU of vitamin D, and 3.7 IU of vitamin E per gram. 5 Nutrient analysis measured on weekly samples of dietary ingredients (CP and NDF). Fat content as reported by NASEM (2016). 6 Formulated to provide 330 mg/animal of monensin (Rumensin) and 90 mg/animal of tylosin daily (Tylan, Elanco Animal Health). 1
were fed the grower diet for 77 d before adaptation to the finishing diet. The GRW calves were then slaughtered on December 20 (160 d on feed). Ractopamine hydrochloride (Optaflexx; Elanco Animal Health) was included (300 mg/head daily) in the common finishing diet for the last 28 d on feed for all cattle every year. Weights were collected over 2 consecutive days at trial initiation. Before collecting weights, calves were limit fed a common diet for a minimum of 5 d to minimize gastrointestinal weight variation (Watson et al., 2013). For calves in the GRW treatment, ending BW for the growing phase was used as initial BW for the finishing phase. In yr 1, a 4% shrink was applied to calves in the GRW treatment upon completion of the growing phase due to calves not being limit fed before collecting weights on 2 consecutive days. In yr 2 and 3, GRW calves were limit fed between phases before collecting weights on 2 consecutive days. To obtain a common physiological endpoint between treatments, ultrasonography was used to detect 12th rib fat thickness on GRW cattle approximately 40 d before projected slaughter date each year. The ultrasound scans were then used to set slaughter date by targeting backfat thickness to be equal to FIN cattle. All cattle were slaughtered at Greater Omaha Packing Co. (Omaha, NE). On the day of slaughter, HCW and liver abscess scores were recorded. Following a 48-h chill, 12th rib fat thickness, marbling score, and LM area were recorded. Final BW, ADG, and G:F were calculated on a carcass-adjusted basis using a common DP of 63%. Yield grade was calculated using the following equation (USDA, 2016): 2.5 + (6.35 × 12th rib fat depth, cm) − (2.06 × LM area, cm2) + (0.2 × KPH, %) + (0.0017 × HCW, kg).
Economic Analysis A 10-yr (2007–2016) economic analysis was conducted to compare postweaning management systems. Data were collected from the time of weaning through slaughter. Days spent in each phase and performance data from the current study were used to determine costs, revenue, and net return on a dressed pricing basis. For initial purchase price, calf prices were collected from Schulz (2017) to determine 10-yr average purchase price for weaned calves (Table 2). To account for differences in weaning weights between cow-calf production systems, a price slide of $17.23/45 kg was used. The price slide was based on a regression of a 10-yr average price of steer and heifer calves weighing 226 to 272 kg and a 10-yr average price of steer and heifer calves weighing 272 to 318 kg. When calculating feed costs, all costs were calculated on a DM basis. Cash corn prices were collected from Johanns (2017) to determine a 10-yr average corn price of $0.18/kg ($4.59/25.45 kg). The costs of distillers grains and Sweet Bran were calculated as 100% of the value of corn (DM basis). Base price for grass hay and wheat straw was $50 per 907 kg. An additional $15 per 907 kg was charged to grass hay and wheat straw to account for grinding cost.
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Supplement was priced at $200 per 907 kg. Interest rates for agricultural operating loans were collected from the Federal Reserve Bank of Kansas City (2016). A 10-yr average interest rate of 6.2% was applied to the total operating cost associated with each phase and half of the initial animal cost. Feedlot yardage was held constant at $0.45 per head per day for all treatments. Similarly, all steers and heifers were charged $15 per head for health and processing fees. Actual morbidity of calves on each treatment was similar and minimal (12 animals treated in total); therefore, a standard fee of $15 was charged to all treatments. A 10-yr average live cattle price as reported by Schulz (2017) was adjusted to a 63% DP to determine selling price ($1.83/0.45 kg) on a dressed basis. Total revenue was calculated by multiplying dressed selling price by HCW. Total costs included initial purchase cost with interest plus operating costs associated with the growing or finishing phase or both. Net return was then determined by subtracting total costs from total revenue. Cost of gain (COG) in each phase was calculated by dividing costs associated with each phase (not including purchase price of the animal) by the BW gained during the phase.
Statistical Analysis Data were analyzed using the mixed procedure of SAS (SAS Institute Inc., Cary, NC) as a completely randomized design. Experimental unit was pen (24 total) with cow-calf production system, postweaning management, and the cow-calf × postweaning interaction included in the model as fixed effects. Location and year were included as random effects. Because the proportion of steers and heifers varied within pen, proportion of steers within each pen was included as a covariate for all variables.
RESULTS AND DISCUSSION Growing Phase Performance of GRW cattle during the growing phase is presented in Table 3. Initial BW was lighter for calves that had previously been wintered on cornstalks compared with calves wintered in the dry lot (P = 0.02). However, GRZ calves had greater ADG (P = 0.03) and tended to have greater DMI (P = 0.09) and improved feed efficiency (P = 0.07) compared with DL calves. There was a 33-kg difference in initial BW and a 21-kg difference in ending BW for the growing period; therefore, the GRZ cattle compensated by 12 kg (36%). Compensatory growth is a period of nutrient (typically energy or protein) restriction followed by a period of relatively fast growth (NASEM, 2016). The response is due to a combination of factors including increased efficiency and energy utilization, decreased organ mass, and increased intake (Fox et al., 1972; Horton and Holmes, 1978; Sainz and Bentley, 1997). Compensatory growth has been reported for calves grazing summer grass following
Table 2. Economic assumptions applied to postweaning management systems1 Item Growing phase Yardage, $/animal daily Diet cost, $/907 kg Interest, % Finishing phase Yardage, $/animal daily Health and processing, $/animal Diet cost, $/907 kg Interest, % Cattle prices Feeder calf price,2 $/0.45 kg Feeder calf price,3 $/0.45 kg Selling price carcass basis,4 $/0.45 kg Interest, %
FIN
— — —
GRW
0.45 15.00 188.15 6.2 1.53 1.36 1.83
0.45 156.49 6.2 0.45 15.00 188.15 6.2 1.53 1.36 1.83
6.2
6.2
FIN = calves directly adapted to finishing diet following weaning; GRW = calves fed grower-ration diet for 76 d before finishing phase. 2 The 10-yr average calf price for steers and heifers weighing 226 to 273 kg. 3 The 10-yr average calf price for steers and heifers weighing 272 to 318 kg. 4 The 10-yr average live cattle price adjusted to a 63% DP for calculation of selling price on a carcass basis. 1
corn residue grazing during the winter (Gillespie-Lewis et al., 2015). Compensation by cattle grazing grass following nutrient restriction during the winter has been reported to range from 19 to 88% (Klopfenstein et al., 2000). However in all of these studies, treatments were applied to weaned instead of nursing calves. In the current study, compensatory growth by GRZ calves was likely due to both increased DMI and efficiency and did carry over into the finishing phase.
Finishing Phase No significant cow-calf production by postweaning management interactions were observed for any finishing performance variables tested (P ≥ 0.15; Table 3). Cattle that were previously wintered on cornstalks had lighter initial BW entering the finishing phase than cattle that had been wintered in the dry lot (P < 0.01). However, GRZ cattle had a compensatory response characterized by greater (P ≤ 0.02) ADG and G:F and a tendency (P = 0.08) for greater DMI during finishing compared with DL cattle. Previous research has also reported that cattle have increased DMI (Mader et al., 1989; Sainz et al., 1995) and compensatory gain (Carstens et al., 1991; Sainz et al., 1995; Neel et al., 2007) following a period of growth restriction.
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Table 3. Effects of postweaning management and cow-calf production system on finishing performance and carcass characteristics1 FIN Item Growing performance Days on feed Initial BW, kg Ending BW, kg DMI, kg/d ADG, kg G:F Finishing performance Days on feed Initial BW, kg Final BW,3 kg DMI, kg/d ADG, kg G:F Carcass characteristics HCW, kg LM area, cm2 12th rib fat, cm Marbling4 Calculated YG
DL
— — — — — 196 279 594 9.4 1.61 0.172 374 87.7 1.40 424a 3.3
GRW GRZ
DL
— — — — — 196 251 589 9.6 1.73 0.180 371 89.0 1.32 422a 3.1
76 284 377 7.9 1.22 0.155 169 377 631 9.9 1.48 0.150 399 89.7 1.52 438a 3.4
P-value GRZ
SEM
76 251 8 356 8 8.3 0.5 1.37 0.054 0.167 0.019 169 356 10 621 15 10.3 0.4 1.58 0.044 0.152 0.004 391 10 88.4 1.9 1.52 0.14 491b 15 3.4 0.2
Postweaning
— — — — — <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 0.66 0.06 <0.01 0.04
Cow-calf
0.02 0.11 0.09 0.03 0.07 <0.01 0.15 0.08 <0.01 0.02 0.15 0.92 0.65 0.05 0.44
Int.2
— — — — — 0.62 0.65 0.60 0.80 0.15 0.64 0.15 0.65 0.04 0.33
FIN = calves directly adapted to finishing diet following weaning; GRW = calves fed grower-ration diet for 76 d before finishing phase; DL = winter dry-lot feeding of cow-calf pair before weaning; GRZ = winter corn-residue grazing of cow-calf pair before weaning. 2 Test for cow-calf production by postweaning management interaction. 3 Calculated on a carcass-adjusted basis using a common DP of 63%. 4 Marbling score: 400 = small, 500 = modest, and so on. 1
When evaluating the effects of postweaning management on finishing performance, GRW cattle had greater initial BW, final BW, and DMI compared with FIN cattle (P < 0.01). However, cattle in the FIN treatment had increased ADG and subsequently improved G:F compared with GRW cattle (P < 0.01). Although results from the current study are generally consistent with previous data evaluating calf-feds and yearlings, the age of calves used in the current study varied from typical calf-feds and yearlings. The GRW and FIN cattle were almost 9 mo old at the onset of postweaning treatments. Consequently, FIN cattle were older than typical calf-feds at feedlot placement. However, GRW cattle were similar in age (12 mo) to short-yearlings upon entering the finishing phase. Previous data suggest that calf-feds have lower DMI, similar ADG, and improved feed efficiency compared with short-yearlings (Adams et al., 2010). Although the responses observed for DMI and G:F of the FIN and GRW cattle are similar to that of calffeds and yearlings, daily gain during finishing was greater for FIN cattle compared with GRW cattle. The relatively fast rate of gain during the 76-d growing period may have influenced subsequent finishing daily gain of GRW cattle.
Lancaster et al. (2014) observed that stocker-phase ADG was inversely related to finishing ADG and G:F, indicating that greater rate of gain during the stocker phase is followed by slower rate of gain and worsened feed efficiency during the finishing phase. Initial finishing BW may also affect ADG during finishing. Initial finishing BW of GRW cattle was almost 100 kg heavier than initial BW of FIN cattle. Similar to the responses observed in the current study, Reinhardt et al. (2009) observed that finishing ADG declined as initial finishing BW increased. In contrast, other researchers have reported that BW at the onset of finishing is positively related to finishing ADG (Reuter and Beck, 2013; Bittner, 2016). Furthermore, Reuter and Beck (2013) reported that initial finishing BW is a more powerful predictor than stocker ADG when predicting finishing performance. Differences in cattle (genetics, age, BW) as well as feed quality and quantity during both the growing and finishing periods may explain some of these differences. Furthermore, as discussed by Reuter and Beck (2013), BW at time of feedlot entry is confounded with season, previous ADG, and length of the growing period. Length and severity of nutrient restriction affect a calf’s ability to compensate
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(Fox et al., 1972). Calves in the current study on the GRZ treatment would have had minimal nutrient restrictions, although it is difficult to model because intake and forage quality measurements always contain some assumptions in grazing situations.
Carcass Characteristics A significant postweaning management effect was observed for HCW, with cattle in the GRW treatment producing 23-kg-greater carcass weight than FIN cattle (P < 0.01; Table 3). Twelfth rib fat thickness tended to be greater for GRW cattle relative to FIN cattle (P = 0.06). A significant postweaning management by cow-calf production interaction was observed for marbling (P = 0.04). Cattle in the GRW-GRZ treatment had greater marbling compared with cattle in the GRW-DL, FIN-DL, or FINGRZ treatments, which were not different from each other. A postweaning management effect was also observed for calculated YG, with GRW cattle having greater YG than FIN cattle (P = 0.04); however, the biological significance of this is unclear.
The increase in HCW of GRW cattle is in agreement with Adams et al. (2010), who observed a 37-kg increase in HCW for short-yearlings compared with calf-feds. In that study, short-yearlings and calf-feds were slaughtered at similar 12th rib fat thickness. Klopfenstein et al. (2000) illustrated the importance of comparing cattle at equal fat endpoints, especially when cattle are fed in different feeding programs. Bruns et al. (2004) reported that increased DOF resulted in increased HCW, fat thickness, and marbling. Because equal 12th rib fat thickness was not obtained between treatments in the current study, it is difficult to determine whether the difference in performance between the 2 postweaning systems was due to treatment or from feeding the GRW cattle to the point in which 12th rib fat thickness was increased. Because GRW cattle were slaughtered at greater fat thickness, it is interesting that marbling of GRW-DL cattle did not increase to the same degree as marbling of GRW-GRZ cattle. This suggests that marbling can be affected by nutrition before the finishing phase (Pethick et al., 2004). However, it is difficult to draw strong conclusions from marbling data with
Table 4. Economic analysis of cattle by postweaning management and cow-calf production system1 FIN Item Growing phase Purchase cost3,4 Diet cost3 Yardage cost3 Interest cost3 Growing COG5 Finishing phase Purchase cost3,4 Diet cost3 Yardage cost3 Interest cost3 Health and processing cost3 Finishing COG5 System (growing + finishing) Total revenue3,6 Total operating cost3 Total COG5 Net return3,7
DL
— — — — — 891.72 379.61 88.05 30.87 15.00 71.81 1,502.61 513.53 71.81 97.11
GRW GRZ
— — — — — 834.44 388.32 88.00 30.19 15.00 68.28 1,488.49 521.54 68.28 132.04
DL
P-value GRZ
SEM
Postweaning Cow-calf
894.80 835.70 15.34 — 104.94 109.24 8.58 — 34.35 34.35 — — 7.63 7.30 0.28 — 70.14 63.63 7.33 — — — — 14.8 — 351.06 360.63 19.19 <0.01 76.24 75.90 1.81 <0.01 25.64 24.95 1.21 <0.01 15.00 15.00 — — 81.82 79.46 1.71 <0.01 1,585.23 1,578.89 36.86 <0.01 614.86 627.36 26.78 <0.01 77.93 74.39 2.27 <0.01 76.12 116.27 18.35 0.16
0.04 0.17 — 0.11 0.12 0.01 0.14 0.86 0.24 — 0.01 0.46 0.30 0.01 0.01
Int.2
— — — — — — — 0.94 0.90 0.99 — 0.53 0.77 0.82 0.99 0.84
FIN = calves directly adapted to finishing diet following weaning; GRW = calves fed grower-ration diet for 76 d before finishing phase; DL = winter dry-lot feeding of cow-calf pair before weaning; GRZ = winter corn-residue grazing of cow-calf pair before weaning. 2 Test for cow-calf production by postweaning management interaction. 3 Variables presented as $ per animal. 4 Calculated by multiplying BW by 10-yr average steer and heifer price in 45.4-kg weight groups. 5 Cost of gain (COG; $/45 kg) calculated by dividing costs associated with each phase (animal purchase cost and interest on the animal not included) by the BW gained during the respective phase. 6 Calculated by multiplying HCW by dressed selling price. 7 Total revenue − (total operating cost + purchase cost). 1
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limited numbers (Owens and Gardner, 2000), and genetics can overshadow nutrition effects on marbling (Hocquette et al., 2010; Moisá et al., 2014).
Economic Analysis No significant cow-calf production by postweaning management interactions were observed for any economic variables tested (P ≥ 0.53; Table 4). Due to differences in initial BW, initial purchase cost during the growing phase was greater if calves had previously been wintered in the dry lot compared with calves wintered on cornstalks (P = 0.04; Table 4). There were no significant differences between treatments for growing costs (P ≥ 0.11) or growing COG (P = 0.12). Growing COG was numerically lower for GRZ calves as a result of greater daily gain during the growing phase. Likewise, initial purchase cost and COG during the finishing phase were greater for DL calves compared with GRZ calves (P = 0.01; Table 4). When evaluating the main effects of postweaning management on finishing variables, finishing costs were greater (P < 0.01) for FIN cattle compared with GRW cattle, largely due to FIN cattle having 27 more DOF during the finishing phase. Conversely, finishing COG was less (P < 0.01) for FIN cattle compared with GRW cattle due to FIN cattle having improved feed efficiency during finishing. For the economics of the weaning through slaughter portion of the system, GRZ cattle had less overall COG (P = 0.01; Table 4), which was a reflection of the improved feed efficiency observed for GRZ cattle relative to DL cattle. Although similar revenue (P = 0.46) was generated between treatments, GRZ cattle produced $38 greater net return than DL cattle (P = 0.01) as a result of reduced initial purchase cost of GRZ cattle. Because of increased HCW, GRW cattle generated $86 greater total revenue in relation to revenue received from FIN cattle (P < 0.01). However, FIN cattle had decreased total operating cost and COG (P < 0.01). Net return was $18 greater for FIN cattle but not statistically different between FIN and GRW cattle (P = 0.16). In the current analysis, the growing diet was 83% the cost of the finishing diet ($156/907 kg ÷ $188/907 kg). In order for net return to be equal between the GRW and FIN treatments, the cost of the growing diet would need to be 70% ($132 per 907 kg) of the cost of the finishing diet.
APPLICATIONS Calves wintered on cornstalks alongside their dams consistently responded with compensatory growth during the feedlot growing and finishing phases. Cattle wintered on cornstalks weighed less at the onset of postweaning treatments compared with cattle that had been wintered in the drylot. However, HCW was similar between treatments. Using a relatively rapid growing phase (76 d) on cattle before the finishing phase produced greater HCW and
generated more revenue compared with cattle directly adapted to a finishing diet following weaning. However, improved feed efficiency and greater daily gain of cattle directly adapted to the finishing diet resulted in similar net return relative to cattle fed a grower diet before being finished. Wintering lactating cow-calf pairs on corn residue is an economical option in Nebraska. Growing calves before the feedlot phase results in greater HCW but not always improved net return.
ACKNOWLEDGMENTS Funding was provided by the Dr. Kenneth and Caroline Eng Foundation.
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