New Zealand Journal of Agricultural Research abstracts
Feed conversion efficiency, daily pasture intake, and milk production of
primiparous Friesian and Jersey cows calved at two different liveweights
T. R. MACKLE1
C. R. PARR1
G. K. STAKELUM2
A. M. BRYANT1
K. L. MacMILLAN1
1Dairying Research Corporation
Private Bag 3123
Hamilton, New Zealand
2Teagasc Agricultural and Food Development
Authority
Moorepark Research Centre
Fermoy
Co. Cork, Ireland
Abstract Pasture dry matter intake (DMI), milk yield and
composition, and calculated feed conversion efficiencies (FCE), were monitored
throughout lactation for primiparous Friesian (n = 16; F) and Jersey
(n = 16; J) cows calved at either high (H) or low (L) calving
liveweights (CLW). Half of the cows within each breed were differentially fed
(H versus L) during the 8 weeks before expected calving date to produce CLWs of
404 (FH), 354 (FL), 334 (JH), and 277 (JL) +/- 14 (SED) kg. Animals were fully
fed on pasture as one group after calving throughout lactation. J cows were
more efficient than F cows in converting DM into solids-corrected milk (SCM)
(1.63 versus 1.49 +/- 0.07 kg/kg DMI), milksolids (MS) (129 versus 115 +/- 5
g/kg DMI), milk fat (79 versus 67 +/- 3.8 g/kg DMI), and metabolisable energy
intake (MEI) into milk energy (43 versus 37 +/- 1.8%). Average DMI measured
during six periods across lactation and once after the completion of lactation,
were higher for F than J cows (10.5 versus 8.6 +/- 0.2 kg/cow per day) but CLW
had no effect on average DMI. CLW did however, affect DMI at 215 days since
calving (DSC) when LCLW cows consumed more DM (FH, 11.3; FL, 12.0; JH, 9.4; JL,
10.2 (0.4 kg DM/cow per day). Liveweight-corrected DMI were slightly greater
for J cows (2.66 versus 2.55 +/- 0.05 kg/cow per day per 100 kg LW). The HCLW
cows lost LW while LCLW cows gained LW until 56 DSC (FH, -8.9; FL, 33.4; JH,
-25.9; JL, 10.4 ( 8.5 kg LW/cow), with JH cows losing more than FH (P
< 0.01). The LCLW cows produced less (P < 0.01) milk, SCM,
protein, milk fat, and lactose over the first 30-56 DSC. Thereafter,
differences between CLW groups were not significant. Average daily milk yield
across the whole lactation was affected by CLW (12.2 versus 11.0 (0.6 kg/cow
per day; HCLW versus LCLW). LCLW cows had higher concentrations of milk protein
(38.5 versus 36.1 +/- 0.8 g/1000 g) and milk fat (57.1 versus 54.1 +/- 1.5
g/1000 g). It was concluded that J cows were more efficient converters of
pasture DM into MS, primarily because of a greater efficiency in milk fat
production. CLW reduced milk production during the early part of lactation but
did not affect DMI until mid lactation.
Keywords Friesian; Jersey; cows; alkanes; dry matter intake;
milk; protein; milk fat; feed conversion efficiency
New Zealand Journal of Agricultural Research, 1996, Vol. 39: 357-370
0028-8233/96/3903-0357 $2.50/0 (c) The Royal Society of New Zealand
1996
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