A theoretically-based model for predicting total digestible nutrient values of forages and concentrates

This experiment compared growth, physiological, and reproductive responses of beef heifers with (MI) or without (CON) access to a creep-feeder, as a manner to stimulate metabolic imprinting while nursing their dams. On day 0, 60 Angus × Hereford heifers were ranked by BW and age (140 ± 3 kg and 68 ± 3 days), and assigned to pairs so all ranking criteria were similar between heifers within each pair. On day 1, pairs were randomly assigned to MI (n = 15) or CON (n = 15). From day 1 to 51, MI pairs and their dams were allocated to 15 drylot pens where heifers had ad libitum access to a corn-based supplement through a creep-feeder. The CON pairs and their dams were maintained in an adjacent single drylot pen. From day 52 to 111, treatments were managed as a single group on a semiarid range pasture. On day 111, heifers were weaned and allocated to two pastures (one pasture/ treatment), receiving hay and a corn-based concentrate until day 326. Heifer BW was recorded before and at the end of the creepfeeding period (day 1 to 51), and on days 112 and 326. On days 0, 51, 111, 187, 261, and 325, jugular blood was collected and real-time ultrasonography for longissimus muscle depth and backfat thickness assessment was performed. Blood was also collected every 10 days from days 113 to 323 for puberty evaluation via plasma progesterone. Liver and subcutaneous fat biopsies were performed on days 51, 111, 261 and 325. Average daily gain was greater ( P < 0.01) for MI than CON from day 1 to 51, tended ( P = 0.09) to be greater for CON than MI from day 112 to 326, while BW on day 326 was similar between treatments. On day 51, MI had greater ( P ⩽ 0.01) plasma IGF-I and glucose concentrations, as well as mRNA expression of hepatic pyruvate carboxylase and adipose fatty acid synthase than CON. On days 261 and 325, plasma insulin concentrations were greater ( P ⩽ 0.03) in CON than MI. Mean mRNA expression of hepatic IGF-I and adipose peroxisome proliferator-activated receptor gamma were greater ( P ⩽ 0.05) in MI than CON. No treatment effects were detected for puberty attainment rate. In conclusion, supplementing nursing heifers via creep-feeding for 50 days altered physiological and biochemical variables suggestive of a metabolic imprinting effect, but did not hasten their puberty attainment.Keywords: growth, heifer, physiology, puberty, supplementation ImplicationsFeeding a high-concentrate supplement to nursing beef heifers for 50 days did not enhance their post-weaning body development, physiological responses, and puberty attainment. However, supplemented heifers had long-term increases in biochemical variables suggestive of metabolic imprinting, which is defined as biological responses to a nutritional intervention during early life that permanently alters physiological outcomes later in life. Perhaps a longer period of creep-feeding may be required to further increase supplement intake in nursing beef heifers, and effectively enhance body and reproductive development via metabolic imprinting effects. † E-mail: reinaldo.cooke...

Section: Samplingmentioning

confidence: 99%

“…Puberty attainment was declared at the first sampling that resulted in plasma progesterone ⩾1.0 ng/ml. On days 51, 111, 261 and 325, liver and subcutaneous fat Calculated according to the equations described by Weiss et al (1992). samples were collected via biopsy immediately after each blood sampling.…”

Section: Samplingmentioning

confidence: 99%

Creep-feeding to stimulate metabolic imprinting in nursing beef heifers: impacts on heifer growth, reproductive and physiological variables

Cooke

Cappellozza

Marques

et al. 2015

“…Historically, the energy content of forages was estimated using empirical singlecomponent equations based on specific nutrients such as NDF, ADF or crude fibre (Mertens, 1992;Rotz et al, 1999;Ferreira and Mertens, 2005). A summative approach was adopted by dynamic nutritional models (Sniffen et al, 1992; -E-mail: francesco.masoero@unicatt.it National Research Council (NRC), 2001; Robinson et al, 2004) to estimate the net energy for lactation (NE L ) content of forage on the basis of their total digestible nutrient (TDN) values and considering the level of intake of animals (Weiss et al, 1992;Weiss, 1998). The empirical and summative approaches differ mainly in the number of parameters required to estimate NE L .…”

Section: Introductionmentioning

confidence: 99%

Use of principal component analysis to classify forages and predict their calculated energy content

Gallo

Moschini

Cerioli

et al. 2013

A set of 180 forages (47 alfalfa hays, 26 grass hays, 52 corn silages, 35 small grain silages and 20 sorghum silages) were randomly collected from different locations of the Po Valley (Northern Italy) from 2009 to 2010. The forages were characterised for chemical composition (11 parameters), NDF digestibility (five parameters) and net energy for lactation (NE L ). The latter was calculated according to the two approaches adopted by the 2001 Nutrient Research Council and based on chemical parameters either alone (NE L3x-Lig ) or in combination with 48 h NDF degradability in the rumen (NE L3x-48h ). Thereafter, a principal component analysis (PCA) was used to define forage populations and limit the number of variables to those useful for obtaining a rapid forage quality evaluation on the basis of the calculated NE L content of forages. The PCA identified three forage populations: corn silage, alfalfa hay and a generic population of so-called 'grasses', consisting of grass hays, small grain and sorghum silages. This differentiation was also confirmed by a cluster analysis. The first three principal components (PC) together explained 79.9% of the total variation. PC1 was mainly associated with protein fractions, ether extract and lignin, PC2 with ash, starch, NDF and indigestible NDF (iNDF) and PC3 with NDF digestibility. Moreover, PC2 was highly correlated to both NE L3x-Lig ( r 5 20.84) and NE L3x-48h ( r 5 20.94). Subsequently, forage-based scores (FS) were calculated by multiplying the original standardised variables of ash, starch, NDF and iNDF with the scoring factors obtained from PCA (0.112, 20.141, 0.227 and 0.170, respectively). The FS showed a high determination coefficient for both NE L3x-Lig ( R 2 5 0.86) and NE L3x-48h ( R 2 5 0.73). These results indicate that PCA enables the distinction of different forage classes and appropriate prediction of the energy value on the basis of a reduced number of parameters. With respect to the rumen in situ parameters, iNDF was found to be more powerful at discriminating forage quality compared with NDF digestibility at different rumen incubation times or rates of NDF digestion.

“…Other models for predicting energy and nutrient values of ruminant feeds also employ relationships between lignin and NDF, but using a 0.667 power (Weiss et al, 1992;Weiss, 1993 and1999). Van Soest (1994) presented separate equations for lignin determined by sulphuric acid or potassium permanganate and these equations included the proportion of lignin contained in the ADF, instead of NDF.…”

Section: Resultsmentioning

confidence: 99%

Substitution of crude cell wall for neutral detergent fibre in the equations of the Cornell Net Carbohydrate and Protein System that predict carbohydrate fractions: application to sunflower (Helianthus annuus L.)

Queiróz

Fukushima

Gomide

et al. 2008

Prediction of carbohydrate fractions using equations from the Cornell Net Carbohydrate and Protein System (CNCPS) is a valuable tool to assess the nutritional value of forages. In this paper, these carbohydrate fractions were predicted using data from three sunflower (Helianthus annuus L.) cultivars, fresh or as silage. The CNCPS equations for fractions B 2 and C include measurement of ash and protein-free neutral detergent fibre (NDF) as one of their components. However, NDF lacks pectin and other non-starch polysaccharides that are found in the cell wall (CW) matrix, so this work compared the use of a crude CW preparation instead of NDF in the CNCPS equations. There were no differences in the estimates of fractions B 1 and C when CW replaced NDF; however, there were differences in fractions A and B 2 . Some of the CNCPS equations could be simplified when using CW instead of NDF. Notably, lignin could be expressed as a proportion of DM, rather than on the basis of ash and protein-free NDF, when predicting CNCPS fraction C. The CNCPS fraction B 1 (starch 1 pectin) values were lower than pectin determined through wet chemistry. This finding, along with the results obtained by the substitution of CW for NDF in the CNCPS equations, suggests that pectin was not part of fraction B 1 but present in fraction A. We suggest that pectin and other non-starch polysaccharides that are dissolved by the neutral detergent solution be allocated to a specific fraction (B 2 ) and that another fraction (B 3 ) be adopted for the digestible cell wall carbohydrates.