Supplementation of grass silage-based diets with small quantities of concentrates: strategies for allocating concentrate crude protein

AbstractFifty-five multiparous Holstein-Friesian cows were used to evaluate the short- and long-term effects of varying the crude protein (CP) content of concentrates offered at a low level (5 kg/day) along withad libitumaccess to a high quality grass silage. Three dietary treatment groups in lactation weeks 4 to 22 received concentrates containing either 156 (L), 247 (M) or 338 (H) g CP per kg dry matter; from weeks 13 to 21, half of the L animals changed over to the H concentrate and vice versa so that there were five treatment groups (LL, LH, MM, HL and HH). Feeding M or H compared with L increased silage voluntary intakes (P&lt;0·05) and the yields of milk (P&lt;0·05), fat (P&lt; 0·05) and protein (P&lt; 0·01). Milk protein concentration increased with level of concentrate CP (P&lt; 0·05). Pattern of concentrate CP supply (comparison ofLH, MM and HL) had no significant effect on intake or yields of milk and milk solids across the experiment (weeks 4 to 21), though cows gained less weight on treatment HL than on LH (P&lt;0·05) or MM. Intake, milk and component yields were all markedly affected by a change in concentrate CP at week 13; there were positive effects of additional CP (LLv.LH) and negative effects of reduced CP (HHv.HL) on silage intake (P&lt;0·05), as well as milk yield (P&lt; 0·001), milk protein yield (P&lt; 0·001) and milk protein concentration (P&lt; 0·001). Responses to increased concentrate CP were of a similar magnitude in early and midlactation; extra concentrate CP can recover depressed yields and concentrations of milk protein in established lactation. Production responses to concentrate CP involved a concomitant increase in silage voluntary intake.</jats:p

Life history, breeding biology and movement in a new species of carnivorous marsupial, the buff-footed antechinus (Antechinus mysticus) and a sympatric congener, the subtropical antechinus (Antechinus subtropicus)

Antechinus are one of just a few mammal genera worldwide which exhibit semelparous reproduction. Consequently, the life history of many antechinus has been well studied. However, in the last few years, several new species have been described in the genus and their ecology is little known. Here, the first multi-year ecological study of breeding, growth and movement in one of these species, the buff-footed antechinus, Antechinus mysticus, was undertaken. Over a 2-year period, monthly capture-mark-recapture data from two geographically close sites (~2.5 km apart) in south-east Queensland, Australia, were collected. At one site, the subtropical antechinus, Antechinus subtropicus, also occurred. This allowed the investigation of possible competitive effects between this larger Antechinus species and A. mysticus. Intensive trapping across the breeding season of A. mysticus also allowed the growth rates of pouch young of a wild antechinus population to be calculated for the first time. Results showed that A. mysticus followed the synchronous, semelparous breeding strategy seen in all congeners. Male A. mysticus were last caught in August, and females gave birth in September. Average distance moved by A. mysticus was comparable with congeners. Competition with A. subtropicus may affect A. mysticus because A. mysticus weighed more and males moved further when not in sympatry with A. subtropicus. However, female A. mysticus moved further when in sympatry with A. subtropicus, confounding clear interpretation. Overall, the life history information obtained for A. mysticus provides a foundation for further research and will aid the conservation management of this new species