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Rural Industries Research & Development Corporation
Summary of full report
by RC Mulley and JS Flesch University of Western Sydney, Hawkesbury campus
June 2001
RIRDC Publication No 01/0095
RIRDC Project No UWS-16A
Executive Summary
This study describes a number of experiments undertaken to assess the nutritional requirements of pregnant and lactating fallow does with the aim of enhancing production and quality assurance in the Australian Deer Industry. Areas of study include determination of metabolisable energy intake of farmed fallow deer does of two genotypes throughout pregnancy and lactation, metabolisable energy intake of fallow deer fawns from 12 to 20 weeks of age and the effects of restricted maternal nutrition on foetal and placental development at different stages of gestation. In conjunction with nutritional adequacy, a body condition scoring system based on ante-mortem and post-mortem descriptors was developed for fallow deer.
Over the two consecutive breeding seasons of 1997-98 and 1998-99, multiparous European fallow does (n=12) and multiparous hybrid (¼ Mesopotamian, ¾ European) fallow does (n=12) were individually housed and fed ad libitum one of two concentrate rations throughout the second and third trimesters of pregnancy and 12 weeks into lactation. Daily energy intake, patterns of liveweight change and fawn birthweight were measured.
In parallel, patterns of liveweight gain and reproductive performance of pasture-fed fallow does (n=36) were monitored. Statistical analysis of the metabolisable energy intake for penned does over two years produced no significant differences between years and between genotypes (P=0.05) allowing data on energy intake requirements from the two genotypes over pregnancy and lactation to be combined. Individually housed does consumed on average 10.3 MJME/day (0.54 - 0.69 MJME/kg0.75) during trimester 2 and 13.0 MJME/day during trimester 3 (0.72 - 0.90 MJME/kg 0.75).
Average daily metabolisable energy intake over the first 12 weeks of lactation was shown to be double that of non-pregnant fallow does (Mulley et al 2000) at 20.4 MJME/day.
Compared with data for non-pregnant European and Hybrid fallow does (Mulley et al 2000) that consumed 3248 and 3697 MJME annually, pregnant European and Hybrid does in this study consumed on average 3666 and 3684 MJME over the 238 day period from week 11 of pregnancy through to the end of 12 weeks of lactation, with lactation accounting for 57% and 50% of annual ME intake for E and H does respectively. These data show that daily feed requirements effectively double following parturition, and farmers should feed budget, introduce supplements and or adjust stocking rates after trimester 2 through to the end of lactation to accommodate this increased feed demand.
Following the 1997-98 breeding season, individually housed does (n=12) were liberated, thus weaning them from their 12 week old fawns, which were fed the same concentrate ration they had been observed to consume with their mothers from 6 weeks of age onwards. Over the next 8 weeks, daily metabolisable energy intake and weekly liveweight change were monitored. It was found that both male and female fawns consumed in excess of 10.5MJME/day (0.95-1.1 MJME/kg 0.75), highlighting that weaner fawns have a similar, if not higher energy requirement than non-pregnant adult does. This high energy requirement suggests pre-rut weaning should be employed to offer adequate pasture availability for weaners to reach slaughter weight / joining weight.
The investigations into feeding behaviour of fallow deer consisted of the monitoring of individually housed concentrate-fed pregnant does (n=6), and pregnant pasture-fed fallow does (n=9). Feeding behaviour of individually housed pregnant fallow does was monitored 24 hours a day, 7 days a week from August 1997 to March 1998 when fawns were weaned. Pasture-fed does (n=9) were monitored at regular intervals for two 7-day periods during trimester 3 (1997) and mid lactation 1998.
All individually housed does conformed to 3 main periods of feeding activity over a 24-hour period, starting before sunrise and ending 2.5 (SEM±0.45) hours later. The second main period of feeding occurred just prior to sunset (P<0.01) also lasting for 1.7 (SEM±0.52) hours. The third and most prolonged period of feeding occurred around midnight (P<0.01) lasting for 2.3 (SEM±0.52) hours.
Temperature had a significant effect on feed intake. It was shown that temperatures above 35oC during a recognised period of feeding activity (sunrise and sunset) reduced the amount of time spent feeding (P=0.002). Reduced feeding time during periods of high temperature also suppressed average feed intake over a 24-hour period (P=0.02). Conversely, average ambient temperatures over a 24-hour period below 20oC during recognised periods of feeding increased the average length of time by each doe spent at the feed trough (P=0.033). Does also spent on average greater time feeding at other times of the day when temperatures were below 15 oC. Temperatures in between these maximum and minimum thresholds had no significant effect on time spent at the feed trough, or on feed intake. The increase in MEI over the first 6 weeks of lactation (P=0.000) was reflected by the increased number of visits to the feed troughs, with individual visits being significantly higher (P<0.001). The increase in feeding activity during lactation was positively correlated with MEI, although there were statistical differences between timing or duration of feeding events between the high and low energy rations (P=0.506).
Observations of pasture-fed does suggest that morning feeding activity starts before daylight and steadily declines 1.5-2 hours after sunrise, while afternoon feeding activity commences approximately 1.5-2 hours before dusk and intensifies at sunset. Individually housed does also displayed a similar periodicity of feed intake, although there were much stronger feeding periods around midday and midnight.
A 5 point body condition score (BCS) system was developed from live and carcass measurements from over 350 fallow deer. Deer were assigned a BCS based on live animal palpation, with scores ranging from 1 (emaciated) to 5 (overfat). Alternative methods of estimating body condition were also evaluated, including bone marrow fat concentrations (BMF), the kidney fat index (KFI), circulating levels of betahydroxybutyrate (b-OHB), hot standard carcass weight (HSCW), chest girth and animal height. Measurements of fat depth on the rump, loin, brisket and shoulder on carcasses were used to confirm live animal palpation. There were significant differences in fat depth levels between all BCS’s at the rump, loin and brisket (P<0.001). The correlation between BCS and depth of fat over the forequarter was not significant across all BCS grades (P=0.515). Fat depth at the rump, loin and brisket were all found to be correlated with BCS (P<0.001).
KFI and BMF were shown to be useful indicators of body condition. There was a linear relationship (r2 = 0.847, df = 77, P<0.001) between BCS and KFI. This relationship is described by the equation y = 0.02243x + 1.292, where y = BCS and x = KFI. There were significant differences in levels of BMF between BCS grades 1 and 2 (P<0.001) and between BCS 2 and 3 (P<0.001). There was no significant difference in BMF% between BCS 3 and 4 (P=0.256). While some of the other methods of estimating BCS showed levels of significance between individual scores, they were largely inconsistent and of little practical value to the live animal and meat processing sectors of the deer industry.
The effects of restricted maternal nutrition on rates of liveweight gain, BCS and conceptus development were evaluated over two consecutive breeding seasons. Does over the first year of the study (n=12) were group-fed at the maintenance requirements for non-pregnant fallow does (Mulley et al 2000), produced no significant differences in placental mass, foetal weight, crown-rump length, circulating b-OHB concentrations and rates of doe liveweight gain at the end of the first, second and third trimesters of pregnancy when compared with group-fed ad libitum does. Feed restrictions in the second experiment were reduced to 70% of the daily metabolic bodyweight energy intake of ad libitum fed individually housed pregnant does, with all animals slaughtered at 12 weeks gestation.
While there was no significant treatment effect on conceptus development, ad libitum fed does had a higher mean liveweight than restricted intake does (P=0.043) and a higher mean BCS (P=0.001). It was concluded that while the level of maternal energy restriction had no significant effect on conceptus development over the first 12 weeks of gestation, the reductions in doe liveweight and BCS compared with ad libitum-fed does indicated that had the level of maternal restriction been taken to term, fawn viability may have been compromised.
Precise strategic feeding of red and fallow der breeding stock is now possible, which should lead to more consistent reproductive performance and higher quality slaughter animals. Furthermore, use of strategic feeding in conjunction with BCS systems for both species will lead to better resource management and profitability, as farmers consistently produce animals to specification.
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