New Zealand Journal of Agricultural Research abstracts
Short communication
Seasonal changes of
herbage quality within a New Zealand beef cattle finishing pasture
C. F. Machado
Facultad de Ciencias Veterinarias
(UNCPBA), Pinto 399
Tandil (7000), Argentina
S. T. Morris*
J. Hodgson
M. Fathalla
College of Sciences
Massey University
Private Bag 11 222
Palmerston North, New Zealand
*Author for correspondence.
Abstract To estimate seasonal variation in herbage
quality from a Friesian bull beef production system, 50 hand-plucked
herbage samples were taken approximately every 2 weeks from paddocks
about to be grazed at the Tuapaka bull beef unit, Massey University,
between December 1998 and February 2002. The pastures were perennial
ryegrass and white clover. Herbage mass (kg DM ha–1) was
estimated using a calibrated rising plate meter. Herbage samples were
assessed for crude protein (protein), lipid, ash, acid detergent fibre
(ADF), neutral detergent fibre (NDF), non-structural carbohydrates
(NSC), organic matter digestibility (OMD) and metabolisable energy
content (ME) by near infra-red spectroscopy. A correlation analysis
between variables was performed and an analysis of variance was carried
out by month and season using year as a block. Additionally, a Bayesian
smoothing analysis was applied to the complete data set of ME and
protein. Fibre variables (NDF and ADF) had the strongest relationship
between themselves and with other variables, and were negatively
related to NSC, ME, and protein. The content of non-structural
carbohydrates was positively associated with herbage ME and protein.
Values of herbage quality were high throughout the measurement period
(80.6% OMD, 11.3 MJ ME kg–1 and 25.8% protein). Protein
levels for autumn, winter, spring, and summer were 26.4, 26.7, 26.9,
and 23.3%, and ME levels were 10.9, 11.6, 11.8, and 10.9 MJ ME kg–1,
respectively. Non-structural carbohydrates had the highest variability
(31% coefficient of variation), followed by the fibre variables (15 and
16% for ADF and NDF respectively). In the smoothing analysis, both ME
and protein showed a seasonal behaviour with a tendency for herbage
protein to peak before ME in spring. Seasonal variation of specific
nutrients and implications for animal performance are discussed, with
particular reference to the influence of high herbage protein levels on
protein and energy utilisation.
Keywords herbage quality; seasonal change; beef;
protein; energy
A04009; Received 26 January 2004; accepted 17 December 2004; Online
publication date 30 May 2005
New Zealand Journal of Agricultural Research, 2005, Vol. 48:
265–270
0028–8233/05/4802–0265 © The Royal Society of New Zealand 2005
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