Sudangrass is a summer forage grass, which is adapted to a long sowing period from late April to early August in
warm regions of Japan. However, yield loss is sometimes caused by weed competition because early growth of sudangrass
is affected by air temperature. Here, we investigated crop–weed competition of sudangrass on 2 sowing dates (late May:
mean air temperature, 19.6°C; mid-July: mean air temperature, 27.1°C) and 3 interrow space (17 cm, 30 cm, and 75 cm)
by measuring canopy cover degree of sudangrass, dry matter yield, and dry matter weight of weeds. When sudangrass
was sowed in late May, cover degree changed on the basis of interrow space. When interrow space was 17 cm and 30 cm,
cover degree was about 90% at 28 days after sowing (DAS) and 42 DAS, respectively. However, when interrow space
was 75 cm, cover degree reached up to 69%, even at 42 DAS. Interrow space also affected sudangrass yield and weed
weight. Sudangrass yield for interrow spaces 17 cm, 30 cm, and 75 cm was 884, 625, and 482 kg/10 a, and weed weight
was 3, 36, and 92 kg/10 a, respectively. Thus, for sowing in late May, preferable interrow space was considered to be 17
cm for weed suppression and high yield. For sudangrass sowed in mid-July, cover degree was about 90% at 27 DAS for
interrow spaces 17 cm and 30 cm. Even for interrow space 75 cm, cover degree was about 90% at 42 DAS. Sudangrass
yield for interrow spaces 17 cm, 30 cm, and 75 cm was 971, 925, and 814 kg/10 a, and weed weight was 0, 0, and 12 kg/10
a, respectively. Mean air temperature was higher in mid-July than in late May; therefore, early growth was superior in
mid-July, and suppressed weed growth was observed. These results showed that for sudangrass sowing in mid-July, preferable
interrow space is less than 30 cm for weed suppression and a high yield. In conclusion, to suppress weed growth
and obtain a high yield, sudangrass interrow space should be set at about 17 cm, especially in a low air temperature season
such as May. However, in case the interrow space cannot be set at 17 cm or if there are many weeds, sowing date of sudangrass
should be set in a high air temperature season such as July, because high temperatures promote the early growth
of sudangrass and reduce weed competition.
In the present study, we determined effectiveness of electric fences on wild boar (Sus vittatus leucomystax)’
s invasion into a cattle fattening barn. We conducted a survey using camera trapping to determine the
frequency of wild mammals observed in a cattle fattening barn from February 2011 to January 2012. The
total number of visits to the cattle fattening barn by wild boars, Japanese badgers (Meles meles), raccoon dogs
(Nyctereutes procyonoides), and feral cats (Felis catus) were 8,152, 186, 169, and 30, respectively. The wild
boars often passed under net fences set at the gate of the cattle fattening barn during observation periods.
After invasion, the wild boars consumed leftover concentrates in the feed trough.
In the second experiment, the effects of electric fences comprising 2-stage (one at 15 cm and the other at
30 cm) electric wires (which harbored voltage and pulse intervals of approximately 3,000 V and 1.3 s, respectively)
on cattle fattening barn wild boar invasions was investigated from February 2012 to January 2013.
The wild boar exhibited exploratory behaviour near the electric fences, using its snout, and subsequently received
an electric shock. Thereafter, adult wild boars avoided the fences. Thus, no adult wild boar invasions
in the cattle fattening barn were noted the year after fencing. It was found that 19 piglets invaded the barn
in February 2012; however, there were no piglet invasions in the cattle fattening barn during the remaining
11 months. These findings indicate that 30-cm-high electric fences effectively prevent wild boar invasions in
cattle fattening barns.
Eight pregnant cows were used to determine the effects of feeding total mixed ration (TMR) silage containing
20% of steam-rolled corn grain (corn group) or 20% of cracked brown rice (rice group) on prepartum
dry matter intake (DMI), digestibility before parturition, plasma metabolite and milk production. There were
no significant differences in TMR intake of both groups before parturition. There were no significant differences
in apparent digestibility of dry matter (DM), crude protein (CP), ether extract (EE), neutral detergent
fiber (NDFom) and acid detergent fiber (ADFom) of cows between corn group and rice group before parturition.
The apparent NFC digestibility of cows in rice group was significantly higher than that of corn group
(P<0.05). Dietary treatment did not affect the milk yield, milk fat, protein and lactose content. These results
indicated that cracked brown rice can be used for prepartum dairy cows as substitute for corn grain.
The objectives of this study were to (1) obtain fundamental information on the presence of wild Sika
deer (Cervus nippon) in grasslands and (2) investigate the effectiveness of two fencing methods for reducing
the damage to meadows invaded by wild Sika deer. We designed two experiments. The first experiment was
conducted from January 2014 to December 2015. We used a light census survey to determine the frequency
of occurrence of wild Sika deer in grasslands within the Iriki Livestock Farm, which is the Experimental
Farm maintained by the Faculty of Agriculture at Kagoshima University. Sika deer were observed on nights
throughout the study period, within and outside of the grasslands. The monthly average number of deer visiting
the grasslands was 179. The monthly maximum number was 270 (April 2014), and the minimum was
97 (November 2015).
In the second experiment during February to March 2015, we investigated the behavioural responses of
wild Sika deer to two types of fences (a physical protective mesh fence with a height of 175–200 cm, and a
5-wire electric fence with a height of 140 cm) enclosing 2 ha of meadow. Seven Sika deer passed through
gaps under the physical protective mesh fence. Of the 27 Sika deer observed near the electric fence, 14 of
the animals explored the fence but ultimately avoided it. The remainder of the observed Sika deer entered the
meadow, most of them passing through the electric fence without touching the wires.
These findings indicate that Sika deer do depend on the grasslands within livestock farms and that more
effective methods for preventing Sika deer invasions are urgently needed.
Beef production contributes to environmental problems, such as climate change, air pollution, and water
pollution. The present study aimed to compare the environmental impact of the conventional fattening
system for Japanese Brown beef steers (housed and fed large amounts of concentrate) with a year-round
grazing system. We first evaluated the environmental impacts of the two beef fattening systems (year-round
grazing and conventional) through life cycle assessment, then assessed the environmental impacts of the
conventional cow-calf system. The impact of each system was determined regarding its potential contribution
to global warming, acidification, and eutrophication, as well as its energy consumption. From these results
and an evaluation of the carcass characteristics, we estimated and compared the environmental impacts per
unit carcass weight of beef produced by the two fattening systems. The carcass weights were 403 kg (age at
slaughter: 25.3 months) in the year-round grazing system and 465 kg (age at slaughter: 25.0 months) in the
conventional system. The year-round grazing system led to lower environmental impacts per unit body weight
gain of steers during fattening compared with the conventional system with reductions in the global warming,
acidification and eutrophication potentials, and energy consumption of 22, 87, 81, and 57%, respectively.
Unlike the conventional system, imported feed was scarcely used in the year-round grazing system. This led
to a reduction in the environmental impacts associated with feed transportation, the major factor contributing
to the reduction of all the impact categories we assessed. The impacts on global warming, acidification,
and eutrophication potentials, and energy consumption per kg carcass weight of beef in the conventional
system were 30.1 kg CO2eq., 326.7 g SO2eq., 38.0 g PO4eq., and 210.9 MJ, respectively, and in the year-round
grazing system 27.8 kg CO2eq., 153.2 g SO2eq., 20.3 g PO4eq., and 134.2 MJ, respectively. Consequently, the
year-round grazing system led to a reduction in the environmental impacts per unit carcass weight of beef
compared with the conventional system, with reductions in global warming, acidification, and eutrophication
potentials of 8, 53, and 47 %, respectively, and in energy consumption of 36%. We can therefore conclude
that introducing year-round grazing into a conventional beef fattening system can mitigate the environmental
impacts of Japanese beef production.