Faecal near infrared reflectance spectroscopy estimates of diet quality and responses to nitrogen supplements by cattle grazing Bothriochloa pertusa pastures
D. B. Coates A C and R. M. Dixon BA Davies Laboratory, CSIRO, PMB, PO, Aitkenvale, Townsville, Qld 4814, Australia.
B Department of Primary Industries and Fisheries, PO Box 6014, Rockhampton, Qld 4702, Australia.
C Corresponding author. Email: david.coates@csiro.au
Australian Journal of Experimental Agriculture 48(7) 829-834 https://doi.org/10.1071/EA08004
Submitted: 4 January 2008 Accepted: 20 March 2008 Published: 20 June 2008
Abstract
A grazing experiment in the seasonally dry tropics of north Queensland examined the diet selected and the growth responses of Bos indicus steers to urea supplement over two dry seasons and one wet season, from August 2001 to January 2003. There were two groups of 10 steers (control and urea-supplemented) and each group comprised two age cohorts, A and B, of five steers each with an age difference of ~1 year. In June 2002, cohort A steers were replaced with steers 2 years younger (cohort C). The steers grazed Bothriochloa pertusa pastures on a low fertility Red Chromosol soil. The groups were switched between two adjoining paddocks at fortnightly intervals when they were weighed and faecal samples were collected for faecal near infrared reflectance spectroscopy (F.NIRS) estimates of diet quality and growth rate. Rainfall and diet quality followed the expected seasonal pattern, but the 2001–02 wet season was very short (November–January) with only 65% of the long-term average rainfall. There was no rain during the 2001 dry season (DS-1) from August to mid November, and no effective rain (17 mm) between February and December 2002. Non-grass (i.e. herbaceous dicot plants) made only a small contribution to the diet, averaging 13%. In DS-1 and in the dry season of 2002 (DS-2) diet crude protein (CP) averaged 2.5% and 2.9%, and DMD/CP (ratio of dry matter digestibility to CP) averaged 18.6 and 17.1, respectively. Liveweight (LW) loss in control steers during DS-1 averaged 32 kg. Urea supplement reduced LW loss by 18 kg (P < 0.001), but most of the benefit was lost during the following growing season. During the extended dry period in 2002, average LW losses of control steers were 85 and 47 kg in the older and younger cohorts, respectively, and supplementation with urea reduced weight losses by 53 and 31 kg, respectively (P < 0.001). F.NIRS predicted the cumulative LW of the unsupplemented steers in cohorts A and B with acceptable accuracy, the difference between the observed and predicted final LW being 6 kg for cohort A after 10 months, 12 kg for cohort B after 17 months, and 27 kg for cohort C after 7 months. The results demonstrated that F.NIRS can be effectively used to monitor dietary CP and DMD levels in grazing cattle, to help develop an understanding of cattle responses to urea supplement relative to the quality of the basal forage diet, and to provide useful decision support information for the nutritional management of grazing cattle.
Acknowledgements
We wish to acknowledge Meat and Livestock Australia for their financial support. We wish to thank Mr John Brownson for access to facilities and cattle at Forest Home Station, Mike Nicholas and Kylee Verry for technical support, and Christina Playford and David Reid for discussion and assistance with statistical analysis. The experimentation was conducted under Animal Ethics approval.
Coates DB, Dixon RM
(2007) Faecal near infrared reflectance spectroscopy (F.NIRS) measurements of non-grass proportions in the diet of cattle grazing tropical rangelands. The Rangeland Journal 29, 51–63.
| Crossref | GoogleScholarGoogle Scholar |
Dixon RM, Coates DB
(2005) The use of faecal NIRS to improve the nutritional management of cattle in northern Australia. Recent Advances in Animal Nutrition in Australia 15, 65–75.
Dixon RM,
Smith DR, Coates DB
(2007) Using faecal near infrared reflectance spectroscopy to improve nutritional management of breeders in the seasonally dry tropics. Recent Advances in Animal Nutrition in Australia 16, 135–145.
Foster AH, Blight GW
(1984) Liveweight response of cattle grazing native pasture in southeast Queensland when supplemented with urea/molasses in winter and spring. Tropical Grasslands 18, 131–137.
Graham TWG,
Wood SJ,
Knight JL, Blight GW
(1983) Urea and molasses as a winter supplement for weaner steers grazing improved pasture in Central Queensland. Tropical Grasslands 17, 11–20.
Hennessy DW, Williamson PJ
(1990) Feed intake and liveweight of cattle on subtropical native pasture hays. 1. The effect of urea. Australian Journal of Agricultural Research 41, 1169–1177.
| Crossref | GoogleScholarGoogle Scholar |
Lyons RK, Stuth JW
(1992) Fecal NIRS equations for predicting diet quality of free-ranging cattle. Journal of Range Management 45, 238–244.
| Crossref | GoogleScholarGoogle Scholar |
McLennan SR,
Dunster PJ,
O’Rourke PK, Murphy GM
(1981) Comparison of dry season urea supplements containing salt, sulphur or molasses for steers grazing native pasture in the dry tropics of northern Queensland. Australian Journal of Experimental Agriculture and Animal Husbandry 21, 457–463.
| Crossref | GoogleScholarGoogle Scholar |
McLeod MN, Minson DJ
(1978) The accuracy of the pepsin-cellulase technique for estimating the dry matter digestibility in vivo of grasses and legumes. Animal Feed Science and Technology 3, 277–287.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
Winks L,
Laing AR, Stokoe J
(1972) Level of urea for grazing yearling cattle during the dry season in tropical Queensland. Proceedings of the Australian Society of Animal Production 9, 258–261.
Winks L,
Laing AR,
O’Rourke PK, Wright GS
(1979) Factors affecting response to urea-molasses supplements by yearling cattle in tropical Queensland. Australian Journal of Experimental Agriculture and Animal Husbandry 19, 522–529.
| Crossref | GoogleScholarGoogle Scholar |