Calf ADG Research Articles

176 Relationships Among Early Life Weight and Growth Among Halfblood Bos Indicus Male Calves and Associations with Carcass Weight

Abstract Nellore-Angus steers (n = 572) born in 2009-2013, 2015, and 2019 and Brahman-Angus reciprocal steers (n = 73) born in 2019 and 2020 were evaluated for calf and carcass weights (HCW). Calves were born and reared at the McGregor Research Center and included F2, F3, F4, and F5 Nellore-Angus and F1 Brahman-Angus. Calves were weighed at 4 approximate times: within 48 h of birth (BWT), 50 d age (spring-working, SWWT, not available for 2009-2010), 180 d age (pre-weaning, PRWWT), and approximately 210 d age (weaning, WWT). Animals born in the same year were managed similarly, and cow herds were managed together in most cases except during annual natural service, multi-sire breeding seasons. Animals born in the same year were managed as contemporaries post-weaning and for feedlot finishing. Mixed model analyses of variance for calf traits included genetic type (nested within calf birth year), calf birth year, age of dam category, and covariates of Julian birth date (BWT, SWWT) or calf age (PRWWT and WWT) as fixed effects. In each year at least 2 genetic types were present; however, because of imbalance across years, only genetic types produced in the same years were compared following significant F-tests. For these analyses cow age category did not affect calf BWT or SWWT, but showed influence for PRWWT (P = 0.006) and WWT (P < 0.001); cow age category did not affect calf ADG. Differences in calf weights (P < 0.001) and calf ADG (P < 0.001) due to the genetic type were driven by reciprocal differences between Brahman-Angus crosses and potential maternal hybrid vigor advantages for F2 Nellore-Angus calves from F1 dams vs. other genetic types. Brahman-sired F1 (B × A) males were 12.7 to 14.1 kg heavier for BWT (P < 0.001) and 14.9 to 19.2 kg heavier for SWWT (P < 0.001) than Angus-sired F1 males (A × B), but persistence to weaning varied across years. It appears in these data that some genetic types may be more sensitive to individual year effects, but it is uncertain why. Correlations of calf weight traits with HCW were inconsistent across genetic types. No calf weight was associated with HCW in A × B crosses, and only PRWWT in B × A related to HCW (r = 0.44, P = 0.007). Among Nellore-Angus crosses, BWT showed small to moderate correlation to HCW (0.23 < r < 0.46); however, among the F4 and F5 calves, later weights (SSWT, PRWWT and WWT) had large correlations with HCW (0.50 < r < 0.79) whereas these correlations ranged from 0.24 to 0.37 in F2 and F3 steers. It appears animals of similar Bos indicus percentage may have quite different calf growth patterns related to HCW.

Calf Performance Offspring of Cow Fed with Depolarizing Katuk Leaves

The birth and growth of dairy calves are important factors in the dairy cattle business. The growth of calves and mothers needs to be monitored in production management so that they can produce good seeds or milk according to the expected quality. This study aims to determine the effect of feeding depolarized katuk leaves on the performance of calves from cow consuming depolarized katuk. 21 gestation cows were three groups of seven cows each, the control group (feed complete),CF-DKPo (complete feed added with Depolarized Katuk Powder), CF-DKPe (complete feed added with Depolarized Katuk Pellets). As a feed addition, 100 grams of depolarized katuk feed were provided daily to each head which is given in the morning by mixing it with the morning feed. The treatment was served during at 10 days before calving day and up to 7 days birth. The research data consisted of gestational days data, daily gain data and calf body weight data from 0 – 90 days old. Data analysis on gestational age, body weight, and average daily gain of calf were by using one-way analysis of variance (ANOVA), and if there is a difference, continue with further testing (Dunnett’s test) using SPSS. The results showed that there were differences in birth weight and body weight in calves from mothers that were given depolarized katuk leaves. Calves from broodstock that consumed depolarized katuk leaves in pellet form had higher weights compared to the control and BKD treatments. Significant differences occurred in birth weight and calf ADG for each treatment. Katuk leaves that have been depolarized can be added to feed to help calves grow bigger.

Performances of Post-weaned Pasundan Calves Fed Extra Diets in an Extensive Grazing System

Changing from the pre-weaning to the post-weaning period is a transition from liquid to solid feed accompanied by a dramatic transformation of the GI tract. Supplemental solid feeding of grazing post-weaning calves is expected to improve their productivity. The study aimed to determine the effect of extra diet on the performances of post-weaned Pasundan calves (15 males and 15 females) that were grazed, using a completely randomized design of 2x3 factorials (two sex factors x three diet factors). The diet treatments were that post-weaned Pasundan calves were grazed: without being given extra diets (grazing/control), extra diets without urea-impregnated zeolite (extra diet-1), and extra diets with urea-impregnated zeolite (extra diet-2). The parameters were diet consumption (only for extra diets, unmeasured grazing consumption), body weights, and body condition. The data were analyzed with GLM Univariate. The results showed: The interaction between diet treatment and sex did not affect all the observed parameters. Consumption of extra diet-1 (529.37±3.06 g DM/head/day) was higher (P0.05) than extra diet-2 consumption (525.17±1.96 g DM/head/day), but after a correction of body weight, the result was no different.  Sex factors did not affect all observed parameters. The ADG of post-weaned calves fed extra diet-1 (155.8±27.5 g), or extra-2 diet (124.2±56.3 g) was higher (P0.05) than the grazing (66.67±35.8 g). The extra diet-1 produced a higher change in body condition (1.8±0.78, P0.05) than extra diet-2 or grazing (1.2±0.42). In conclusion, feeding extra diet-1 to post-weaned Pasundan calves increased ADG by 234% and improved the body condition by 150% better than calves that were only grazed in an extensive grazing system.

Artificial shade as a heat abatement strategy to grazing beef cow-calf pairs in a subtropical climate.

Grazing livestock in subtropical and tropical regions are susceptible to prolonged exposition to periods of extreme environmental conditions (i.e., temperature and humidity) that can trigger heat stress (HS). Currently, there is limited information on the effects of HS in the cow-calf sector globally, including in the southern U.S., as well as on mitigation strategies that could be implemented to improve animal well-being and performance. This study evaluated the impact of artificial shade (SHADE vs. NO SHADE) and breed (ANGUS vs. BRANGUS) on performance of pregnant-lactating cows, nursing heifers, and their subsequent offspring. Twenty-four Angus and 24 Brangus black-hided cows [579 ± 8 kg body weight (BW); approximately 85 d of gestation] and their nursing heifers (approximately 174 d of age) were randomly allocated to 12 'Pensacola' bahiagrass pastures (Paspalum notatum Flüggé; 1.3 ha, n = 4 pairs/pasture), with or without access to artificial shade [NO SHADE BRANGUS (NSB), NO SHADE ANGUS (NSA), SHADE BRANGUS (SB), and SHADE ANGUS (SA)] for 56 d that anticipated weaning during the summer season in Florida. Body condition score (BCS) of cows, blood samples, and BW of cow-calf pairs were obtained every 14 d during the 56-d experimental period until weaning. Following weaning (d 56), treatments were ceased, and cows and weaned heifers were managed alike. Weaned heifers were randomly allocated to 4 pens (n = 12/pen) equipped with GrowSafe feed bunks for 14 d to assess stress responses during weaning via plasma haptoglobin. An effect of SHADE × BREED interaction was detected for cow ADG, BW change, final BW, and final BCS, where SB had the greatest ADG, BW change, final BW, and final BCS. On d 14, SA cows had the greatest concentrations of insulin whereas on d 28 NSB had the lowest concentrations, NSA the greatest, and SA and SB being intermediate. On d 56, SA tended to have the greatest plasma insulin concentrations and SB the lowest. Weight gain per area (kg/ha) tended to be 11.4 kg/ha greater in SHADE vs. NO SHADE pastures. Pre-weaning calf ADG tended to be 0.14 kg greater for SHADE vs. NO SHADE calves. Weaning weight and BW at 14-d post-weaning were lesser for NSB vs. NSA, SA, and SB, whereas no differences in postweaning ADG or haptoglobin were observed. Effects of SHADE × BREED × day interaction was detected on plasma concentrations of IGF-1, in which NSA heifers had the lowest concentrations on weaning day. Gestation length was greater for SHADE vs. NO SHADE cows, but with no impacts on subsequent calf birth and weaning weight. In summary, providing artificial shade to pregnant-lactating beef cows increased body weight gain of nursing heifers and Brangus cows, while no impact on Angus dams were observed. The provision of artificial shade during the first trimester of gestation did not alter growth performance of the subsequent offspring at birth and weaning even though gestation length was longer.

Effects of frequency of concentrate supplementation on performance of early-weaned beef calves consuming annual ryegrass

The objectives of this study were to evaluate the growth performance during a grazing period (experi- ment 1) and forage intake and apparent in vivo digestibil- ity (experiment 2) of early-weaned beef calves consuming annual ryegrass (Lolium multiflorum) and supplemented with concentrate either daily or 3 times weekly. The experiment was con- ducted in Ona, Florida. Treatments consisted of similar weekly concentrate amounts (1% of BW × 7 d) divided into equal amounts and then offered daily (7×) or 3 times weekly (3×) to early-weaned beef calves consuming annual ryegrass pastures from d 0 to 84 (experiment 1) and annu- al ryegrass hay in drylot from d 84 to 105 (experiment 2). From d 0 to 84, reducing the frequency of concentrate supplementation did not influ- ence herbage mass, herbage allowance, or nutritive value of annual ryegrass pastures, or calf ADG, BW, or plasma concentrations of glucose and urea N. The overall forage DM intake was 15% less for 3× versus 7× calves (1.51 vs. 1.78% of BW, respectively). Total DM intake did not differ between 3× and 7× (2.63 vs. 2.73% of BW, respec- tively), whereas in vivo apparent digestibility decreased for 3× versus 7× (85.3 vs. 86.5%, respectively). Reducing frequen- cy of concentrate supplementation from daily to 3 times weekly did not affect overall growth performance of early- weaned beef calves consuming annual ryegrass and can successfully be implemented to reduce feeding costs.

Early Stepdown Weaning of Dairy Calves with Glutamine and Branched-Chain Amino Acid Supplementations.

Simple SummaryWe demonstrated previously that supplementation of glutamine (Gln) at 2.0% of dry matter intake (DMI) increased the rate at which dairy calves achieved ≥1.0 kg/d starter feed intake (SFI) during weaning. Because Gln supplements at <1.0% of DMI or branched-chain amino acid (BCAA) supplements have been shown to improve the performance of weaning piglets, we examined the effects of a lower dose of Gln (8.0 g/d equivalent to 1% of DMI) alone or in combination with BCAA supplementations on SFI and average daily gain (ADG) in this study. Amino acids did not affect SFI or ADG during the supplementations but decreased post-weaning SFI in an additive manner even though the ADG was not affected. The blood analysis on the last day of supplementations revealed a possibility for the Gln and BCAA supplementations to suppress SFI through leptin and serotonin secreted by the gastrointestinal tract.The study objective was to examine the effects of supplementing Gln and BCAA on the SFI and ADG of weaning dairy calves. Holstein heifer calves (11 calves /treatment) at 35 d of age were assigned to: (1) no amino acids (CTL), (2) Gln (8.0 g/d) alone (GLN), or (3) Gln (8.0 g/d) and BCAA (GLNB; 17.0, 10.0, and 11.0 g/d leucine, isoleucine, and valine, respectively) supplementations in whole milk during a stepdown weaning scheme. Calves were weaned completely once they achieved ≥1.0 kg/d SFI. Neither GLN nor GLNB affected SFI or ADG in the first week during weaning. The GLNB decreased SFI compared to CTL, but the SFI was similar between CTL and GLN in the remainder of the weaning scheme. All calves were weaned at 50 d of age. The SFI of GLNB was lower than that of GLN, and the SFI of both GLN and GLNB were lower than CTL post-weaning. The decreased SFI did not alter ADG during weaning or post-weaning. The GLNB tended to have higher plasma leptin and lower plasma serotonin concentrations compared to CTL. Glutamine and BCAA seem to affect the SFI of calves by modulating the secretions of endocrine cells in the gastrointestinal tract.

22 Incorporating Crabgrass in Southern Pasture Systems to Improve Animal Performance

Abstract Bahiagrass (Paspalum notatum L.) is a perennial warm-season forage commonly grown in the Coastal Plains of the Southeastern US, but the nutritive value may not be sufficient for a cow-calf pair. The inclusion of a warm-season annual, such as crabgrass (Digitaria sanguinalis) may improve the forage base when interseeded into bahiagrass monocultures. A three-year summer grazing evaluation was conducted at the University of Georgia Range Cattle Research Station in Alapaha, GA from 2019-2021 to compare concurring production of bahiagrass interseeded with an improved crabgrass (BCG) with bahiagrass monoculture (BG) pastures and animal performance. The experimental design was a randomized complete block with four replications. All paddocks were evaluated on a biweekly basis for herbage availability, botanical composition, and nutritive value. Paddocks (2.6 ha) were continuously grazed using the put-and-take method of stocking with cow-calf pairs, 4 tester pairs per treatment. Pairs were weighed at initiation and on a 28d interval for calculation of calf ADG, cow BCS, and gain/ha. Statistical analyses were conducted using the PROC MIXED procedure of SAS. Average daily gains were analyzed within year and treatment differences were only significant in Y1 (P = 0.05). Forage yield was never limiting in this experiment but CP and TDN were greater (P &amp;lt; 0.001) for BCG when compared to BG for Y1 and Y2. Rainfall was 27cm below average in Y1, therefore these data suggest that during a drought, crabgrass interseeded into bahiagrass can improve the forage nutritive value, and subsequent calf gain, as compared to bahiagrass alone.

89 Relationships Among Measures of Efficiency with Body Weight, Frame Score, and Body Volume in Lactating Multiparous Crossbred Beef Cattle

Abstract Sixty cows of varying frame scores (FS; 5.17 ± 1.38) were used to examine relationships between body size [BW, FS, and body volume (V)] and cow efficiency. Dry matter intake (DMI) and BW change were monitored over 64 days starting 1 month before bull turnout. Cows were fed a forage-based diet and DMI monitored using the Insentec system. Average BW (ABW; 662 ± 93.3 kg) was calculated by averaging 2-d beginning and end BW. Measurements (body length, hip height, hip width, and heart, mid, and flank girth) were collected at the beginning and end of the experiment and average V (628 ± 96.4 L) calculated. Calf BW was recorded at weaning (WW). Pearson partial correlations between body size characteristics and efficiency measures were determined using GLM (SAS) and the MANOVA/PRINTE statement. There was positive correlation (P &amp;lt; 0.001; r = 0.84, 0.74, 0.81) between DMI (kg) and ABW, FS, and V. There was a tendency for negative correlation (P = 0.08, 0.09; r = -0.24, -0.23) between DMI (% of BW) and ABW and V. There was positive correlation (P ≤ 0.05; r = 0.33, 0.28, 0.26) between WW (kg) and negative correlation (P &amp;lt; 0.001; r = -0.63, -0.57, -0.65) between WW (% of ABW) and ABW, FS, and V. There was positive correlation (P = 0.04; r = 0.26) between calf ADG and ABW, and a tendency for positive correlation (P = 0.09; r = 0.23) between calf ADG to weaning and FS. The observed correlations suggest that larger cows consume more kg of feed and wean heavier calves with greater ADG to weaning, whereas smaller cows tend to consume more feed as a percentage of BW and wean a greater percentage of cow BW. Further research is needed on the complex relationship between cow size and efficiency.

Effects of inorganic copper injection in beef cows at late gestation on fetal and postnatal growth, hematology and immune function of their progeny

To determine if Cu injection during late gestation can affect fetal and postnatal growth, hematology and immune function of progeny, 70 multiparous pregnant Angus cows, at 219 ± 15 d of gestation, were ranked by BW and BCS and randomly assigned to one of two treatments: Cu + (n = 35) in total 160 mg of Cu were administered subcutaneously in two moments (80 mg per moment) at 64 ± 15 d and 54 ± 15 d prepartum; and Cu- (n = 35), in total of 16 ml of sterile NaCl solution (9 g / l) were administered subcutaneously in two moments (8 ml per moment) at 64 ± 15 d and 54 ± 15 d prepartum. Calves from both treatments were weaned at 260 ± 15 d of age, male calves were separated from female calves and stockered on natural pastures until 690 ± 15 d of age, then placed into a feedlot for 104 d before slaughter. At the beginning of the experiment, cows Cu serum concentration was similar (P = 0.34) between treatments and these reflected a severe Cu deficiency (Cu + = 24.2 ± 1.5 μg/dl; Cu- = 22.2 ± 1.4 μg/dl). At calving, Cu serum concentration was greater (P < 0.01) in Cu + cows than Cu- cows. Copper serum concentration in calves from Cu + cows was greater at birth (P = 0.02) and 75 ± 15 d of age (P < 0.01) and tended (P = 0.07) to be greater at 160 ± 15 d of age compared to calves from Cu- cows. Calf BW at birth did not differ (P > 0.10) between treatments, however, calf BW adjusted at 75 d of age tended to be greater (P = 0.10) in calves from Cu + cows compared to calves from Cu- cows. Calf ADG from birth to 75 d of age was greater (P = 0.04) in calves from Cu + cows compared to calves from Cu- cows. Calf hematological parameters and titers of neutralizing antibodies against BHV-1 after primary and secondary vaccination against respiratory diseases did not differ (P > 0.10) between treatments. During finishing period, steers BW, 12th rib fat thickness and LM area were not affected (P > 0.10) by treatments. In summary, inorganic Cu injection during late gestation in Cu deficient beef cows allows to increase Cu serum concentration in calves from birth to 160 d of age. This event was associated with an increase in ADG and a tendency to increase BW during the first 75 days of life. After 75 days of age, any effect on the offspring performance was not observed.

75 Management of the Young Calf When Dams Are Limit-fed in Confinement

Abstract Limit-feeding cows in confinement can lower feed costs; however, calves have limited time to access feed. This study was designed to evaluate management options to economically improve calf performance. Calves (n = 54) were stratified by age (105 ± 16 DOA) and assigned randomly to one of nine groups, then each group assigned randomly to one of three treatments: 1) kept with dam with access to cow diet only (PAIRS) 2) early-weaned (EW) or 3) kept with dam with access to creep (CREEP). The cow diet was 54% wet distillers grains (WDGS), 37% straw, and 8% corn. This diet was fed to meet dry cow requirements (7.7 kg DM/d) for EW, lactation requirements (10.9 kg DM/d) in CREEP, and lactation requirements plus allow for some calf intake (14.8 kg DM/d) in PAIRS. The calf diet consisted of 51% alfalfa hay, 25% WDGS, and 22% corn. Calves in the EW had greater (P &amp;lt; 0.01) intake (5.0 kg DM/d) than CREEP (4.1 kg DM/d) from 105 to 203 DOA. Calf ADG differed (P &amp;lt; 0.01) among treatments from 105 to 203 DOA, with CREEP (1.29 kg/d) being greater (P = 0.02) than EW (1.01 kg/d) and both being greater (P ≤ 0.02) than PAIRS (0.74 kg/d). At ~203 DOA, PAIRS and CREEP were weaned and all calves were fed a growing diet. Calf intakes during the growing phase (223 to 314 DOA) did not differ (P = 0.39). However, calf ADG tended (P &amp;lt; 0.06) to differ. The ADG of PAIRS (1.13 kg/d) and EW (1.10 kg/d) did not differ (P = 0.67) but were greater (P ≤ 0.05) than CREEP (0.92 kg/d). However, when calf value and total feed costs were considered, creep resulted in the most return over feed costs at weaning as well as at the end of growing.

Effects of Tall Fescue Endophyte Type and Dopamine Receptor D2 Genotype on Cow-Calf Performance during Late Gestation and Early Lactation.

Grazing endophyte-infected, toxic tall fescue reduces cow/calf production; therefore, this study examines alternate strategies such as use of novel endophyte fescue varieties during late gestation and early lactation or genetic selection of resistant cows. Pregnant cows (n = 75) were randomly assigned to fescue endophyte type: 1) endophyte-infected ergot alkaloid producing tall fescue (E+) or 2) novel endophyte-infected, non-toxic tall fescue (NOV) within maternal (A|A, n = 38 and G|G, n = 37) DRD2 genotype to examine changes in cow/calf performance and milk production during late gestation and early lactation. Grazing E+ fescue pastures during late gestation reduced cow body weight gain but did not alter calf birth weight compared to NOV. Milk production and calf ADG during the first 30 day of lactation were lower for E+ than NOV. The calving rate was reduced, but not calving interval for E+ cows. The adjusted 205-day weight of calves was lower in those grazing E+ with their dams compared to NOV. There were no interactions between DRD2 genotype and fescue endophyte type indicating that genotype was not associated with response to E+ fescue in this study. Overall, grazing NOV tall fescue pastures rather than E+ during critical stages of production improved cow gain during late gestation, calving rate, early milk production and calf growth.

PSIII-8 Impact of SYNOVEX® ONE GRASS implantation during suckling on pre-weaning calf growth performance

Abstract Historic data supports the use of pre-weaning implants to maximize beef calf weaning weight, but their use has declined over the recent decade. A total of 96 beef steers (initially 85.2 kg BW and &amp;gt; 45 d of age) were used in a 168-d study to evaluate the effects of Synovex C® implantation during suckling on pre-weaning calf growth performance. At initial processing, calves were individually weighed and allotted in a completely randomized design to one of two treatments: 1) not implanted (control) or 2) implanted with 150 mg of trenbolone acetate and 21 mg of estradiol benzoate (SYNOVEX® ONE GRASS, Zoetis, Kalamazoo, MI). All calves were weighed on d 0 (implantation), 83, 126 and 168 (weaning), with ADG calculated for each period. Data were analyzed using the GLIMMIX procedure of SAS (v9.4, Cary, NC). There were 48 replicates per treatment, with grazing location as a random effect. While there were no detected differences in BW during the initial phases (P &amp;gt; 0.10), implanted calves tended to have greater (P = 0.100) greater weaning weight than non-implanted calves (279 vs. 265 kg, respectively). Calves implanted with SYNOVEX® ONE GRASS had 0.8, 0.12, and 0.16 kg/d greater (P &amp;lt; 0.05) ADG than those that were not implanted in all three phases. This resulted in an average of 0.10 kg/d greater (P = 0.002) ADG in implanted calves overall compared to the control. In conclusion, this research showed significant increases in suckling calf ADG in implanted calves compared to their non-implanted counterparts, which led to a tendency for 14-kg greater weaning weights. Additional research is warranted to consider the post-weaning growth and impact of re-implanting, but this data reinforces previous literature that suckling calf implantation continues to be cost effective for cow-calf producers.

61 Effects of fescue cultivar on performance of beef cow/calf pairs grazed on summer stockpiled tall fescue pastures

Abstract This 2-year experiment evaluated productivity of wild-type endophyte-infected tall fescue (KY-31) and novel endophyte-infected tall fescue (MaxQ) summer stockpiled (SS) pastures and the performance of fall-calving beef cow/calf pairs grazed on each cultivar. Pregnant Simmental x Angus cows (128 total, 64 each year) were stratified by BW, BCS, and expected calving date, then allotted to 1 of 10 groups. Forage growth was stockpiled from April to initiation of strip-grazing on 31 August of 2017 and 2018. Cows grazed treatment pastures for 52 d from 23 ± 14 d prepartum to 29 ± 14 d postpartum, and calved on treatment pastures. Forage quadrats were clipped from the grazed and ungrazed portions of each pasture to determine weekly forage mass (FM). Total ergot alkaloid (TEA) concentrations were analyzed for all pastures at the beginning of the experiment and every subsequent 2 weeks for KY-31. Cow BW was recorded on 2 consecutive d and BCS determined at the start and end of the experiment. In year 2, ultrasound 12th rib fat thickness (BF) was measured at the beginning and end of the treatment period Milk production was estimated using the weigh-suckle-weigh technique at 29 ± 14 postpartum. In year 1, TEA concentrations for KY-31 pastures did not differ (P &amp;lt; 0.48) over time. Fescue cultivars were not different (P ≥ 0.15) in forage CP, TDN, and grazed or ungrazed FM. Cow BW, BCS, and BF at the beginning and end of grazing were not different (P ≥ 0.41) by treatment. Milk production was higher (P &amp;lt; 0.01) for KY-31 grazed cows. Calving date, calf BW, calf ADG were not different (P ≥ 0.65) by treatment. Neither AI nor overall conception rates differed (P ≥ 0.23) between cultivars. Performance of fall-calving cows pre-exposed to KY-31 was not improved when grazed on MaxQ in a SS system.

126 Pre- and post-partum supplementation of molasses/urea, with or without methionine fortification, to enhance growth and physiology of Bos indicus-influenced primiparous cows and their offspring

Abstract A 2-yr study evaluated the effects of molasses/urea supplementation during pre- and early postpartum, with or without methionine fortification, on growth and physiology of primiparous cows and their offspring. On d 0 of each yr, 36 cows were stratified by BW and BCS (396 ± 54 kg; 5.67 ± 0.66) and randomly assigned to 1 of 12 bahiagrass pastures (3 cows and 1.2 ha/pasture). Treatments were randomly assigned to pastures (4 pastures/treatment) and consisted of no supplementation (NOSUP), 1 kg/d of molasses/urea (MOL; DM basis), or 1 kg/d of MOL + 18 g/d of methionine hydroxy analog (MOLMET; Alimet, Novus, St. Charles, MO). Supplementation began 56 d before parturition (d 0) and ended when all cows within each pasture had calved (d 74). Calves were early weaned on d 147. On d 154, 24 calves (8 calves/treatment) were transferred to individual drylot pens, and offered ad libitum stargrass hay plus soybean hulls-based concentrate DM (75% TDN; 22% CP) at 3% of BW for 47 d. On d 160, calves were vaccinated against bovine viral diarrhea virus-1 (BVDV-1) and parainfluenza-3 (PI-3). Data were analyzed using the MIXED procedures of SAS. Cow BCS at calving was greater (P ≤ 0.05) for MOL and MOLMET vs. NOSUP but the overall percentage of pregnant cows did not differ among treatments (P = 0.82). Calf ADG from birth to drylot exit did not differ (P = 0.83) between MOL and MOLMET but was least (P ≤ 0.04) for NOSUPP calves. Seroconversion to BVDV-1 and PI-3 viruses were greater (P ≤ 0.05) for MOL and MOLMET vs. NOSUP calves. Hence, cow supplementation of molasses/urea during pre- and early postpartum improved cow prepartum BCS, and calf growth and humoral immunity. Methionine fortification of supplements did not impact cow and calf performance.

108 Influence of Cow Body Weight Changes on Calf Growth during the Summer Grazing Period

Abstract In spring calving beef herds, the summer grazing period allows the mature cow to recuperate prior to the next calving season. Cow body weight changes during the summer can vary from minimal to extreme, which may also alter calf growth rates. The objective of this study was to determine the influence of cow body weight changes on calf growth during the summer grazing season. Cows and calves were weighed at the beginning, mid-point and end of the summer grazing season with the end-point being weaning. Based on these weights, cows were categorized into one of four groups: low (LO), medium (MED), high (HI), and extreme (EXT). Groups were determined based on the percent body weight gained across the season with LO being less than 4.99%; 5–9.99% as MED; 10–14.99% as HI, and above 15% as EXT. Data were collected over a 3-yr period utilizing a total of 52 mature Angus cows and 102 Angus calves. Cows were rotationally grazed on mixed grass pastures containing tall fescue and supplemented with corn silage for part of the grazing season. Cows were managed in two groups, but all pastures were grazed by all cows during the season. Calves were provided ad libitum access to creep feed for the entire grazing season. All calves were treated similarly and bulls were left intact until weaning. Data were analyzed in the MIXED procedure of SAS with year and group effects with age of dam as a covariate. Calves had the lowest early ADG in LO cows compared to all other groups (P = 0.01). Overall calf ADG tended to be different between groups as LO cows had slower growing calves compared to EXT or HI dams (P = 0.09). Generally, cows that gained the least amount of weight over the grazing season had slower growing calves.

394 Exploring the relationships between cow-calf management systems as affected by protein/methionine nutrition during gestation on the performance of cow-calf pairs prior to weaning

Abstract A three-way factorial arrangement was used to assess impacts of protein/methionine nutrition during gestation and two lactational management systems on performance of cow-calf pairs pre-weaning. 140 crossbred beef cows were managed in drylot and randomly assigned to one of six nutritional treatments during the third trimester of gestation. Cows were fed to meet 110% (HP), 100% (MP), or 90% (LP) of metabolizable protein requirements for late-gestation (NRC, 2016), with(without) rumen-protected methionine (RPM) for 8 weeks prior to parturition. Post-partum, cow-calf pairs were managed in drylot (DL) and fed ad libitum, a ration formulated to meet lactational nutrient requirements, or rotationally grazed on pasture (PAS). Cow body weights (BW) and body condition scores (BCS) and calf BW were recorded at regular intervals. All data were analyzed using PROC GLIMMIX (SAS v9.4). HP cows were heaviest at calving (P = 0.02), but calf birthweight was unaffected by gestational nutrition (P &amp;gt; 0.19). Gestational nutrition did not impact cow conception rate (CR), or calf BW and ADG (P &amp;gt; 0.17). Lactational management system (PAS, DL) did not affect cow BCS or CR (P &amp;gt; 0.13), but impacted cow and calf BW and ADG. PAS calves were heavier, had greater ADG, and heavier weaning BW than DL calves (P &amp;lt; 0.02). This came at the expense of BW loss throughout lactation and lower ADG for PAS cows, versus BW gains and greater ADG for DL cows (P &amp;lt; 0.0001). An interaction between protein level and RPM supplementation was present for cow BW at calving and weaning, and BW change throughout lactation (P &amp;lt; 0.04), with tendencies for interactions for cow ADG and BCS (P &amp;lt; 0.09). Overall, prepartum protein/methionine supplementation did not affect calf performance prior to weaning, but may have affected cow performance during lactation. Rotationally grazing cow-calf pairs on pasture improved pre-weaning calf gains, but reduced cow gains throughout lactation.

Substituition of urea for soybean meal and forced intake of minerals on the performance of growing crossbred calves

ABSTRACT Forty eight crossbred calves, 24 males and 24 females, with weight and age of 203.6±3.7kg and 11.8±1.0 months were allotted to the following treatments: MT- mineral salt ad libitum and sugar cane mixed with 10g kg-1 mixture of urea and ammonium sulfate in a 9:1 proportion; MA - sugar cane mixed with 16g kg-1 of a concentrate of urea (550g kg-1), ammonium sulfate (60g kg-1) and minerals (390g kg-1); SU - sugar cane mixed with 50g kg-1 of a concentrate of soybean meal (830g kg-1), urea (52g kg-1) and minerals (118g kg-1) and MC - corn silage mixed with 10g kg-1 of a concentrate of urea (500g kg-1), ammonium sulfate (50g kg-1) and minerals (450g kg-1). Minerals mixed with sugar cane (MA) resulted in greater weight gain (0.258 x 0.188kg d-1) for similar intakes of DM (3.29 x 3.30kg d-1). Substitution of part of urea nitrogen in the MA by soybean meal (SU) resulted in greater ADG (0.538 x 0.258kg d-1), due to higher sugar cane intake (4.10 x 3.13kg d-1). ADG of calves receiving corn silage was greater (0.406 x 0.258kg d-1) than for calves receiving sugar cane.

143 Economics of cool-season annuals or reduced labor supplementation systems for wintering cowcalf pairs

Abstract Cattle producers typically feed hay and supplement for a 90 to 120 day window to maintain cows during the winter in Alabama. A 75-day trial evaluated the use of three systems (n = 3 replications per system): 1) rotationally grazed-winter annuals (GWA) on a 14-day rotation, 2) free-choice whole cottonseed (WCS) and bermudagrass hay, or 3) 50% soybean hulls and 50% corn gluten feed (SH:CGF) fed on alternate days at up to 1% BW daily and free-choice bermudagrass hay. GWA had the greatest Total Cost Per Pair Per Day (TCPD) for the 75 day grazing system at $6.58, followed by WCS at $4.73 and SH:CGF at $4.86. Initial and final cow BCS was not different among treatments (P = 0.1558). Cow ADG was greater (P = 0.0370) on GWA than SH:CGF and WCS (0.9, 0.2, and 0.2 kg, respectively), and calf ADG followed a similar pattern (1.5, 1.2, and 1.1 kg/day for GWA, WCS, and SH:CGF, respectively). WCS and SH:CGF were static across trial when only days of trial are considered, but TCPPD decreased linearly (R=.9723) as days on grazing increase. GWA becomes the low cost feed option (with WCS and SH:CGF inputs remaining constant) if trial days were extended to 119 days. This project demonstrates that GWA produces greater animal performance than other project diets, but requires additional grazing days (&gt;119) to be the least cost feeding option.

139 Evaluation of cool-season annuals or reduced labor supplementation systems for wintering cowcalf pairs

Abstract Cattle producers typically feed hay and supplement for a 90- to 120-d window to maintain cows during the winter in Alabama. Relying on stored feeds can increase management system costs and labor needs. The objective of this demonstration project was to compare alternative, reduced labor management systems commonly used by producers in the region for diet quality and animal performance responses. A 75-day trial evaluated the use of three systems (n = 3 replications per system): 1) rotationally grazed-winter annuals (GWA) on a 14-day rotation, 2) free-choice whole cottonseed (WCS) and bermudagrass hay, or 3) 50% soybean hulls and 50% corn gluten feed (SH:CGF) fed on alternate days at up to 1% BW daily and free-choice bermudagrass hay. GWA had the greatest diet digestibility (P &lt; 0.0001), and SH:CGF and WCS were not different from one another (88.7%, 64.3%, and 64.6%, respectively). Diet CP values differed (P &lt; 0.0001) for WGA (21.5%), SH:CGF (13.1%), and WCS (11.2%), respectively. Initial and final cow BCS was not different among treatments (P = 0.1558). Cow ADG was greater (P = 0.0370) on GWA than SH:CGF and WCS (0.9, 0.2, and 0.2 kg, respectively), and calf ADG followed a similar pattern (1.5, 1.2, and 1.1 kg/day for GWA, WCS, and SH:CGF, respectively). This project demonstrates that winter annuals provided 75 days of high-quality winter grazing and resulted in greater animal performance than the other diets. However, all diets provided reduced labor options to maintain cows throughout the winter.

Level and source of fat in the diet of gestating beef cows: II. Effects on the postpartum performance of the dam and the progeny.

A study was conducted to evaluate the effects of level and source of fat in the diet of gestating beef cows on the postpartum performance of the dam and the progeny. Each year, 75 mature pregnant (183±4.8 d until calving) Angus cows with similar BW (663±21.5 kg) and BCS (2.6±0.12; 1 to 5 scale) were randomly assigned to one of 15 outdoor pens. Each pen was assigned to one of three iso-caloric and iso-nitrogenous treatments: a low-fat diet (LF; 1.4±0.12% EE), and two high-fat diets (HF; 3.3±0.20% EE) including a canola seed (CAN) or a flaxseed (FLX) based pelleted feed. Diets were formulated to meet the requirements of pregnant beef cows and fed until calving. Data were analyzed as a randomized complete block design with contrasts for the effects of level (LF vs. HF) and source (CAN vs. FLX) of fat. No differences (P≥0.21) were found for BW or calving to weaning ADG of cows. The average BCS during the first 42 d of lactation was greater (P<0.01) for LF compared to HF (2.63 vs. 2.51) with no difference (P=0.35) for CAN vs. FLX cows. Subcutaneous fat thickness over the ribs was greater (P≤0.01) for LF compared to that of HF cows at calving (5.7 vs. 4.3 mm) and at weaning (4.3 vs. 3.7 mm) with no difference (P≥0.11) for CAN vs. FLX cows. Over the first 42 d of lactation, no difference (P≥0.23) was observed for 12-h milk yield. Milk protein concentration was greater (P=0.03) for CAN compared to FLX (3.11 vs. 3.01%) cows while no difference (P≥0.28) was observed for any other milk component. Milk fat from FLX cows had greater (P < 0.01) CLA and CLnA concentrations than that of CAN cows during the first 42 d of lactation. Pregnancy rate of HF cows tended (P=0.07) to be greater than that of LF cows with no difference (P=0.77) for CAN vs. FLX cows. Calves from HF cows were heavier (P≤0.01) at birth (42.9 vs. 40.2 kg) than those from LF cows. From calving to weaning, ADG of calves born to CAN cows was greater (P=0.03) that that of calves born to FLX cows (1.19 vs. 1.13 kg/d) with no difference (P=0.18) for calves born to LF vs. HF cows. At slaughter, progeny of HF cows had greater (P≤0.03) shrunk BW (605 vs. 579 kg) and HCW (355 vs. 339 kg) compared to those from LF cows with no difference (P≥0.16) for progeny of CAN vs. FLX cows. These results show that feeding a HF diet over gestation results in heavier calves at birth and at slaughter, and superior calf gains from birth to slaughter as well as heavier carcasses, possibly due to a developmental programming effect.