Modeling the Effect of Social Environment on Dry Matter Intake: Time Budget Behaviors and Stocking Density

Presented at 2020 Virtual Cornell Nutrition ConferenceThis talk will cover the development of a mathematical model to account for management decisions on dry matter intake, milk production, and behavior of lactating cows. This preliminary model can be used for evaluation of social environment and its effect on performance.Department of Animal Science Presented at 2020 Virtual Cornell Nutrition Conferenc

Evaluation of models for assessing Medicago sativa L. hay quality

A study was conducted to evaluate current proposed models for assessingMedicago sativa L. hay quality, using near infrared reflectance spectroscopy (NIRS) analyses and Cornell Nett Carbohydrate and Protein System (CNCPS) milk production prediction as a criterion of accuracy. Application of the theoretically-based summative total digestible nutrients (TDNlig) model of Weiss et al. (1992), using lignin to determine truly digestible NDF, explained almost all of the variation in milk yield (MY) (r² = 0.98). However, this model involves high analysis costs to develop and maintain NIRS calibrations and several of its components were poorly predicted by NIRS and therefore, not suited for quality assessment in practice. Current available models (forage quality index (FQI), relative forage quality (RFQ); relative feed value (RFV)) for assessing Medicago sativa L. hay quality revealed lower accuracies (r² = 0.83, r² = 0.76, r² = 0.61, respectively), especially when protein was included in the model (total forage quality index (TFI); r² < 0.49). The developed empirical equation named lucerne milk value (LMV), including ADF, ash and lignin (Y = b0 – b1ADF – b2ash – b3lignin) (r² = 0.96), proved to be the most practical, simplistic, economical and accurate quality evaluation model for commercial application

A model for assessing Medicago Sativa L. hay quality

A study was conducted to identify chemical parameters and/or models for assessingMedicago sativa L. (L) hay quality, using near infrared reflectance spectroscopy (NIRS) analysis and Cornell Net Carbohydrate and Protein System (CNCPS) milk prediction as a criterion of accuracy. Milk yield (MY) derived from the CNCPS model, by replacing the average L hay in a complete diet with 168 representative South African L hay samples, was used as a criterion to evaluate and/or develop models for L hay quality grading. The best single predictor of MY was the acid detergent fibre (ADF) content of L hay, which explained 67% of the measured variation. A multiple linear equation (Y = 64.18 – b1ADF – b2ash – b3lignin) explains 96% of the measured variation in MY. The relatively poor performance of crude protein (CP) (r² = 0.04) and other protein related parameters (r²< 0.25; adjusted-crude protein, ADF-CP, neutral detergent fibre-CP and soluble protein) in predicting MY suggests that protein content of L hay is an unreliable indicator of L hay quality. It is clear that MY derived from the CNCPS model by replacing L hay in a basal diet with others in the South African L hay population can be significantly predicted with high accuracy by the developed empirical model named lucerne milk value (LMV) consisting of only ADF, ash and lignin

The nutritive value of South African Medicago sativa L. hay

A study was conducted to evaluate the variation and expand the existing and limiting nutritive value database ofMedicago sativa L. hay (168 near-infrared reflectance spectroscopy spectrally selected samples) in South Africa. The highest moisture content recorded (140 g/kg) was safely below the critical moisture level of 160 g/kg for effective storage. Coefficient of variation (CV) ranged from 1.2% for dry matter (DM) up to 66.2% for acid detergent fibre-crude protein (ADF-CP). The average ash content was 130 g/kg (73 to 295 g/kg), indicating soil contamination. Fibre fractions varied as follows: acid detergent fibre (ADF) (213 to 473 g/kg), neutral detergent fibre (NDF) (289 to 659 g/kg), lignin (43 to 163 g/kg), cellulose (163 to 364 g/kg) and hemicellulose (53 to 199 g/kg). The mean IVOMD for both 24 and 48 h (693 and 732 g/kg DM, respectively), was representative (CV = ± 8%) of the Medicago sativa L. hay population. Crude protein (CP) (average = 207 g/kg DM) consists of 76.9% true protein. According to ADF-CP, 6% of the samples were heat damaged. High mean Ca (13.5 g/kg), P (25.3 g/kg) and Fe (874 mg/kg) values were recorded

Prediction of chemical composition of South African Medicago sativa L. hay from a near infrared reflectance spectroscopy spectrally structured sample population

The near infrared reflectance spectroscopy (NIRS) to predict chemical and digestibility parameters was investigated. Samples (n = 168) representing the spectral characteristics of the South AfricanMedicago sativa L. hay population were chemically analysed for the development of calibration equations. Values for r² and ratio of prediction to deviation (RPD) used as estimates of calibration accuracy for these parameters were classified as follows: good for dry matter (DM) (r² = 0.97; RPD = 4.84), crude protein (CP) (r² = 0.97; RPD = 4.57), acid detergent fibre (ADF) (r² = 0.95; RPD = 3.97), neutral detergent fibre (NDF) (r² = 0.95; RPD = 3.99), lignin (r² = 0.94; RPD = 3.61), ash (r² = 0.93; RPD = 3.12) and chloride (Cl) (r² = 0.95; RPD = 3.74); intermediate for NDF-crude protein (NDF-CP) (r² = 0.91; RPD = 2.96), sugar (r² = 0.91; RPD = 2.82), in vitro organic matter digestibility at 24 hr (IVOMD24) (r² = 0.90; RPD = 2.84) and 48 hr (IVOMD48) (r² = 0.89; RPD = 2.70); and low (RP