One hundred thirty-seven spring born yearling beef heifers of English breed types were used to determine the relationships between residual feed intake (RFI) and growth rate, body composition, mature size, and fertility. Heifers were housed in a drylot facility during the trial and data were collected over a two-year period (year 1, n=67; year 2, n=70). Individual feed intake, body weight (BW), body condition score (BCS), hip height (HH), and carcass ultrasound measurements (subcutaneous rib and rump fat; RIF and RUF, respectively, longissimus muscle area; LMA, and intramuscular fat; IMF) were collected. Individual feed intakes were expressed as kg of TDN consumed per day and were used to calculate RFI combining both years' data. Heifers averaged 387.0 ± 19.4 days of age (DOA) and 337.1 ± 29.9 kg BW at trial initiation. Mean average daily gain (ADG) was 1.14 ± 0.21 kg/d. A slight relationship (P < 0.05) existed between RFI and both RIF and RUF (r = 0.19 and 0.17, respectively) initially and was increased (r = 0.27 and r = 0.24, respectively; P < 0.01) at trial conclusion. Heifers were classified into groups (POS; mean RFI= 0.74 vs. NEG;-0.73 and HIGH; mean RFI= 1.06, MEDIUM;-0.01, and LOW;-1.13) based on RFI (kg TDN/d), with year of test and farm of origin included in the model as covariates. POS heifers tended to possess more RIF (P = 0.051) and ribeye area (cm 2) per hundred kg of BW (LMACWT) (P = 0.078) than NEG heifers at trial initiation, while LMACWT was greater in POS heifers at trial conclusion (P < 0.01). POSITIVE heifers reached puberty earlier than NEG heifers (414 vs. 427 day, respectively, P = 0.03). MEDIUM heifers exhibited less RIF and RUF (P < 0.05) when compared to either HIGH or LOW at trial initiation. LMACWT was less (P < 0.05) in LOW RFI heifers when compared to HIGH but did not differ (P > 0.10) from MEDIUM females at both beginning and end of test. A negative linear relationship existed between RFI and AGE at PUBERTY (P < 0.05). Each one unit increase in RFI corresponded to a reduction of 7.54 days in AGE at PUBERTY; however, no differences existed between groups in pregnancy or conception rate. Given that RFI was significantly correlated with subcutaneous fat measures and the known relationship between fatness and reproductive maturity, further investigation is warranted. 4. Descriptive statistics for HIGH, MEDIUM and LOW RFI heifers. ……….. 5. BCS and carcass ultrasound traits of POSITIVE and NEGATIVE heifers at trial initiation and conclusion. ……..……………………………………….. 6. BCS and carcass ultrasound traits of HIGH, MEDIUM and LOW heifers at trial initiation. ……………………………………………………………….. 7. BCS and carcass ultrasound traits of HIGH, MEDIUM and LOW heifers at trial conclusion. …… ……………………………………………………….. 8. Change in (final-initial) carcass ultrasound traits of POSITIVE and NEGATIVE RFI heifers. …. ……………………………………………….. 9. Change in (final-initial) carcass ultrasound traits of HIGH, MEDIUM and LOW heifers. ……………………………………………………………….. 10. Phenotypic correlations of RFI with measures of performance, in...

One hundred thirty-seven spring-born yearling beef heifers of British breed types were used to determine the relationships between residual feed intake (RFI) and growth rate, body composition, mature size, and fertility. Heifers were housed in a dry lot facility during the experimental period, and data were collected over a 2-yr period (yr 1, n = 67; yr 2, n = 70). Individual feed intake, BW, BCS, hip height, and ultrasonic measurements [subcutaneous rib fat (UBF), rump fat (URF), LM area (LMA), and intramuscular fat (IMF)] of body composition were recorded. Individual feed intakes (kg of TDN consumed/d) were used to calculate RFI combining both years of data. Heifers averaged 387.0 ± 19.4 d of age and 337.1 ± 29.9 kg of BW at initiation of the experiment. Mean ADG was 1.14 ± 0.21 kg/d during the trial. Based on RFI, with year of test and farm of origin included in the model as covariates, heifers were classified into groups: positive (POS; 0.74 kg of TDN/d) or negative (NEG; -0.73 kg TDN/d) for first analysis and high (HI), medium (MED), or low (LO; mean RFI = 1.06, -0.01, and -1.13 kg of TDN/d, respectively) subsequently. An initial phenotypic relationship (P < 0.05) between RFI and both UBF and URF (r = 0.19 and 0.17, respectively) was sustained (P < 0.01) with UBF (r = 0.27) and URF (r = 0.24) to trial conclusion. No other correlations with RFI were significant. Heifers classified as POS reached puberty earlier than those classified as NEG (414 ± 3.83 vs. 427 ± 4.67 d of age, P = 0.03), and possessed greater LMA per 100 kg of BW (LMACWT) at conclusion of the trial (P < 0.01). Medium heifers exhibited less URF (P < 0.05) compared with either HI or LO heifers at trial initiation. Low heifers possessed less LM area (cm(2)) per 100 kg of BW (P < 0.05) than HI but did not differ (P > 0.10) from MED heifers at either the beginning or the end of test. Additionally, a negative linear relationship was observed between RFI and age at puberty (P < 0.05). Each 1-unit increase in RFI corresponded to a decrease of 7.5 d in age at puberty, but did not affect pregnancy or conception rates (P > 0.10). Differences in body fat and rate of metabolism associated with RFI could delay reproductive maturity.

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Most cow/calf operations in West Virginia are small scale (<100 cows) and calves from multiple operations must be comingled to form marketable lots. Criteria used to establish sale lots are weight, hide color, and USDA feeder cattle grade (FCG). The objective of this study was to determine the impact of hide color and FCG on calf gross sale value (GSV). Results of graded feeder calf sales from fall 2016 (N = 16) and fall 2017 (N = 18) were analyzed totaling 23,859 calves marketed as 2,507 lots. Calves were stratified by sale weight: 136-181 kg (3WT), 182-226 kg (4WT), 227-271 kg (5WT), 272-317 kh (6WT), and 318-362 kg (7WT); hide color: black (BLK) or colored (NBLK), and FCG: LM1, LM2, and non-graded consignor group (CG). Data were analyzed using the PROC GLM procedure of SAS with year and lot size (LS) as covariates. Although numerical differences in GSV existed in the 3WT, 5WT, and 6WT groups ($31.58, $15.00, $11.29/head greater for BLK calves, respectively), only 4WT BLK calves were valued significantly more ($577.22 vs $547.13, respectively; P < 0.01). No value difference was detected in 7WT calves based on hide color. With respect to FCG, no statistical difference was observed in GSV of 3WT and 6WT calves although LM1 3WT calves had a numerical value advantage of $27.73/head and $35.17/head over LM2 and CG calves, respectively, while LM1 6WT calves had a $30.05/head value advantage over LM2 6WT calves. In 4WT and 5WT classes, LM1 calves were valued higher than LM2 calves ($33.75 and $56.96/head, respectively; P < 0.01). Conversely, 7WT CG calves were valued higher than both LM1 ($888.68 vs $838.85/head, P = 0.08) and LM2 calves ($888.68 vs $799.25/head, P < 0.001). Across all weight classes, LM1 calves exhibited a numerical advantage of $37.62/head when compared to LM2 calves indicating optimum FCG is more valuable regardless of weight class. These data also indicate that hide color is less impactful on GSV as sale weight increases.

Technology that facilitates estimation of individual animal intake rates in group-housed settings will result in improvements in animal production and management efficiency. Estimating intake in pasture settings may benefit from models that use other variables as proxies. Relationships among dry matter intake (DMI), animal performance variables, and environmental variables to model DMI were investigated. 202 animals were studied in a drylot setting (153 bulls for 85 days and 55 steers for 55 days) using VYTELLE SENSETM In-Pen-Weighing and Feed-Intake nodes. A machine learning model was calibrated using: DMI, sex, age, full body weight, ADG, water intake, water visit frequency and duration. DMI was positively related to full body weight (r = 0.39, P &lt; 0.001), water intake (r=0.23, P &lt; 0.001), and ADG (r=0.18, P &lt; 0.001). In addition, DMI had significant but weak correlations with water visit frequency (r=0.031, P &lt; 0.001). DMI exhibited weak negative relationships with maximum air temperature (r=-0.094, P &lt; 0.001) maximum relative humidity (r=-0.056, P &lt; 0.001), net radiation (r=-0.040, P &lt; 0.001), and precipitation (r=-0.022, P &lt; 0.001). Weak positive relationships were observed between DMI and maximum wind speed (r=0.031, P &lt; 0.001) and direction (r=-0.022, P &lt; 0.001). The model was validated with resultant average RMSE of 1.06 kg for daily predicted DMI compared to measured daily DMI. In addition, when daily predicted DMI was averaged for each animal, the accuracy of model results improved with RMSE of 0.11 kg. Study results demonstrate that inclusion of water intake and animal performance variables improves predictive accuracy of DMI. Validating and refining the model used to predict DMI in drylots will facilitate future extrapolation to larger group field settings. Vytelle and its logo are trademarks of Vytelle, LLC.