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The strategy of feed adaption for goats in the changing feed sources
supplied from extensive system to semi -intensive one in Central Vietnam
Synthesized paper
Dam Van Tien
Introduction
A feed neophobia is recognized a barrier in supplementation practice where livestock are going to a feedlot, being exported live, being drought fed or fed asupplement which might have a drench or some other medicine in it. Animals areneophobic, which means they are fearful of anything new, for instance, they are scaredof the new feed and the trough and new feed environment. In the previous studies, wefound that ruminants of all ages especially the goat and exotic animals are reluctant toeat novel feed. Therefore, many attempts have been made to reduce the i mpacts of theneophobia on feed acceptance and intake.
For sustainable livestock production in the rural areas of the country where the most of livestock producers are a small scale one (poor farmer), it is important to makebetter use of locally existing feed resources as an supplementary feed for livestockbecause the farmer can not buy more expensive commercial feed. In addition, the wayof promoting feed intake of animals from the agro -byproduct feed resources is also as ameans of reduction of eco-system damage caused by overgrazing from ruminants inuplands and of partial replacement of expensive commercial feed by lower grain dietswhich contained more rich -protein from duckweed and cassava leaf etc. Our study of thematching of feeding behavior of livestock to locally available feed resources may beconsidered as the first intervention in the supplementation strategy for the improvementof animal productivity in the poor communities of the country.
The focus of the researches have been done by our team was to reduce impacts of feed neophobia on feed acceptance and intake. Therefore, the main objective was todetermine the effects of different models of learning about feed on feed acceptance andintake. Thereby, in application, th ose possibilities of learning could become the tacticsfor overcoming feed neophobia in order to shorten the times of training livestock to adaptwith novel feeds. The experiments of the study was tested the effectiveness of threestrategies to reduce feed neophobia occurred when the new feed exposure to livestock.
The first strategy was to offer a new feed in association with a familiar flavor or odor (additives) to animals in order to promote feed acceptance and higher total intakeas compared with similar animals offered the same feeds without additives. In thestudies on the goat, three grasses included Cyperus rotundus L., Cynodon dactylon (L.,)pers, and Brachiaria distachya (L.,) Stapf, were identified by local farmers as beinghighly acceptable to the sheep and goats in the semi -arid area of Phan Rang region(southern part of the central region of Vietnam) were used as additives. The additions ofodor or flavor of native grasses in those studies could be considered the first time testedin both sheep and goats for reducing the time taken by them to begin to eat an ediblefeed (rice bran or both rice bran and rice straw respectively) that they have notpreviously encountered. It is noted that those supplements are the main supplementaryfeed for either ruminants (rice straw) or monogastrics (rice bran). The effects ofunfamiliar odor additives from fresh dog faeces (enemy of sheep) and parasitised goat feces on recognition, acceptance and intake are described to understand the role of odorin distinguishing among the feeds by animals.
The second strategy was to use mothers or other experienced animals to train young ones so that they will recognize feeds that they encounter later in life (Lobato etal. 1980; Tien et al., 1999). The effects of mother to training their offspings to ingest newfeeds on acceptance and intake of young animals after weaning were showed indifferent species, the goat and the pig. The study also was to evaluate if exposure ofpiglets to a feed such as duckwe ed via cues transmitted in milk, or by observation afterbirth but before weaning, influences their post -weaning acceptance and intake of thatfeed.
The third strategy aimed to determine whether fetal experience of mother’s diet , could affect on acceptance and intake of new feed, duckweed after weaning. The studywas done with native pig genotype, Mong Cai and exotic one, Large White andpresented in the first experiment of the Chapter 7. To the best of our knowledge, thefinding from this experiment is the first evidence that such learning in utero occurs.
The last strategy was evaluate if changing height level of feed sources of green feed, mung bean leaf after harvested or none -green feed, rice straw may be increasedthe bite rate and feed intake of the goat, and thereby increased the efficiency of the useof such agro-byproducts offered to the goat in the m ixed farming systems in Vietnam .
This also the first data shows in our current scientific data resources.
Another aspect of supplementation strategy was to determine the nutritive value of prickly-pear cactus, wild plant ( Opuntial Elator), and the way uses it as a supplementaryfeed for sheep. It is noted that this plan is dominant in the rangeland of the semi -aridarea of the country and it is not used for feed purpose. In addition, because of low inprotein content, it could be mixed with either groundnut cake or fish sauce byproductbefore offering to the sheep. The two protein -rich feedstaffs are readily available an dcheep in the study location, Phan Rang region. This finding could be contributed toidentification of local feed supplement resources and to the establishment of feedingadvice to the smallholder farmers in this semi -arid area.
The constraint of feed n eophobia in the use of an un -conventional feed for
livestock in poor communities in Vietnam
One of our findings in our researches was that the main constraint exposed from animal feeding behavior leads to limitation of the use of un -conventional feeds. Thecharacteristic of this impact is a low acceptance and intake of such feeds by animals.
This problem is compounded because less -educated village farmers who live in the poorrural area are generally unaware the fact that such low acceptance ofte n occurs simplybecause the novel feeds are unfamiliar to the animal, and that a considerable amount ofpatience is required in the training of animals to adapt new feeds as well as new feedingsystems.
In addition, in the case of out -door-kept animals, freely grazing in rangelands(traditional practice of ruminant production in Vietnam), the rate of learning about newfeeds is lower in animals that are confined (Tien, 2000 unpublished data).
technique for better use of agro -byproducts (most new feeds) as supplementary feedsfor livestocks is essential in order to replace partly their green roughage intake of ruminants in the forests, and reduce the commercial feed cost in momogastricproduction. The supplementation device now may meet to th e goal of Vietnamesegovernment policy of the development of the animal husbandry sector as a key tool forreduction of poverty in poor rural areas of in the country.
Furthermore, another aspect considered in the thesis was how develop sustainable livestock production in the country. In the mixed farming system, especiallyin lower human population density in mountainous and semi -arid areas, animals are welllooked after especially female ones because principal production objectives arereproduction in order to get more animals for sale and to increase herd size rather thanto promote meat and/or milk productivity. In fact, about 70 percent of ruminant flock arefemale. This means that system characterized by raising male for sale and female forbreeding. In addition, there is an tendency of increasing ruminant production from themountainous area in the country as a mean of exploitation of communal resources withlower input in the production (Tien et al. 1992 and Tien, 2001a). It is clear that, suchsystem is increasing number of ruminants over to other mixed farming systems such ascrop residues or cut and carry systems. Regarding to respect of the exploitation ofcommunal areas, either ruminant producers or other investors such as a rich man fr omurban whom has been investing more capital in raising such livestock especially inrangelands. Because they are aware that investing to extensive ruminant production ismore economic than intensive monogastric one (Tien, 2001b).
Consequently the potential of the mixed farming -communal grazing system to produce more animal products for increasing urban demand but leading to overgrazingand thereby soil error and other negatively environmental impacts will occur. Therefore,in this situation, in our long-term goal we discussed and considered more aboutimportant issue of changing ruminant feeding system from out -door kept one to semi-confinement or confinement by using as much as possible agricultural by -products assupplementary feeds. Thereby, the grazing times might be reduced that will bringbenefits for the environment and the income of poor farmers.
Given that, in our early works from 1997 up till now, we have described the behavioral neophobia constraint occurred in animal produ ction practice in the country bynumber papers on the sheep (Tien, 1997; Tien et al 1997; Tien et al 1999,), on the goat(Tien and Ha, 2000; Tien 2001a;Tien et al 2002b and c), on the pig (Tien 1998, Tien2000; Tien et al 2002 a).
In the following results from our researches we discuss the key issue of feed neophobiaaffected feed recognition, acceptance and intake. Animals in all control groups with nouse of tactics for overcoming their feed neophobia in our researches showed thefollowing facts: Our results of studies have also again confirmed the evidences from previousstudies (Nolan et al., 1975; Lobato et al., 1980; Chapple et al., 1987 a and b) thatfeed neophobia occurred by animals when the new feeds offered to them.
Ruminant animals often are reluctant to eat novel feeds. In fact, the controlsheep did not ingest any rice bran until Day 5 since it was firs t offered to themand likewise control goats did not eat any ri ce straw until Day 9.
In comparison between native and exotic animals in the same species, ourexperiment demonstrated that in the case of naïve animals, the controlled MongCai pigs (native one) began eating new feed (duckweed) on Day 4, whereas thecontrolled Large White pigs (exotic one) did not begin to eat such feed until Day10. It is reasonable to say that a native animal can quickly accept a local feedthan an exotic one.
When novel feeds, rice bran and rice straw, edible and potential in nutr ientsexpose to sheep and goats , we expected experimented animals would eat mor ethose feed, because the ruminants in the research area were in starvation at thattime (heavy drought in 2004 and 2005 ). However, they totally rejected the newfeeds for about one week and then started to ingest the feeds with small amountintake during one week latter. It seems that feed neophobia occurs so thatanimals could avoid toxins in the former period and reduction of potential of over -ingesting toxins may contain in the new feeds in the latter. Thus, we concludedthat when a novel feed offers to animals, a feed neophobia occurs even in thecase of the nutritive feed without toxins.
The question raises from the studies that whether our less -educated farmer can keep their patience about two to three weeks to daily train their livestocks to ingest newfeed. According to our survey made at Trihai village in southern Vietna m (Tien, 2005)animals are rarely supplemented. The lack of supplementation is apparently due to thebelief of villagers that the animals ‘ do not like to eat new type o f feeds’ and thattherefore supplements are unnecessary. While ruminants in the region survive on limitedamounts of poor quality grass during both dry and raining seasons.
Reduction of feed neophobia by adding familiar odor or flavor of native grasses t o
new feeds
The role of flavor in feed preference is complicated. It is argued that on the one hand, preference may be due to flavor because feeds differ in flavor and flavor provideshedonic sensation associated with eating (Grovum, 1988). On t he other hand, feedpreference may be caused by nutrients and toxins, given the importance to survival ofingesting the former and avoiding the latter (Provenza et al., 1992). Feed preferencemay also result from flavor (taste plus smell) and nutrient int eractions such aspostingestive feedback from nutrients and toxins adjusts hedonic value commensuratewith a feed’s homeostatic utility (Provenza, 1995). The early studies showed thatanimals can use flavor to identify feeds (Krueger et al., 1974; Jacobs et al., 1977), andthey relate flavor with the post -ingestive consequences of feeds (Garcia, 1989).
In general, scientists agree that animals select flavor of feeds that will produce positive post-ingestive consequences and avoid the feeds make negative effects. Therewere also many studies to determine the role of flavor on feed acceptance and intake ofwhich familiar flavors added to the new feed to enable animals to discriminate amongfeeds (Furuse et al., 1991; Provenza et al., 1994; Tien et al., 1999; Tien and Ha, 2000).
One of our research objective was to best understanding the role of familiar flavorand odor of native grasses in the research location on feed recognition, acceptance andintake. We hypothesized that the time ta ken by sheep and goats to eat an unfamiliar feed, rice bran or rice straw respectively might be reduced if it was offered in thepresence of a taste or odor that was familiar to the animals (mixed three grasses ofCyperus rotundus L., Cynodon dactylon (L., ) pers, and Brachiaria distachya (L.,) Stapfspecies which were considered as the most feed small ruminants like best by farmers inthe research area, or extended, training time increased if the odor was aversive to them(smells of dog and goat feaces). W e predicted that sheep and goats in the grass -odorand grass-flavor groups actively investigated the rice bran and rice straw respectively,and moved on quickly to ingesting the supplementary feeds.
Interestingly, the results of the experiments were consistent with this hypothesis.
Maximum intake of lambs ate new feed (rice bran) during the test occurred earlier in thegroups added grasses flavor or odor to such new feed than in the control group with thelatter group reaching a plateau value at 9-10 days. During the next consecutive 12 days,intake remained relatively constant and was higher ( P< 0.05) in the flavor than in thegrasses odor group and while the control groups did not differ significantly ( P<0.1). Theoutcomes in the goat experimen t were the same. In this experiment, we found thatmaximum intake of goats ate novel feed (rice straw) during testing occurred earlier in theflavor (grasses taste plus odor) group than in the odor group and both those groupsstarted eating supplement more quickly than the group with no familiar, positive cues(grasses).
Therefore, experimented animals had higher mean intakes during the first 3 weeks of the test than the goats in the control group. However, the intake eventually reached bythe groups receiving familiar, positive cues did not differ significantly after about 3 weeksfrom the time stared to test. The intake of the group tested with the odor of faeces fromparasitised goat was always much lower throughout th e 39 days of testing.
When ruminants are offered unfamiliar feed, neophobia delays its acceptance and intake may be sub-optimal for periods of a week or more. The more rapid acceptance byanimals of a new supplement in the presence of familiar odor or flavor (native gr asses)resulted in a higher cumulative intake of the supplement during this period. Therefore,the conjunction of familiar odors or flavors of native grasses with an unfamiliar feed willincrease its rate of acceptance and shorten the interval between firs t exposure and firstingestion. The findings have implications for tactics that the reduction in feed neophobiaarising through the use of flavor or odor cues familiar to animals, and the higher meanfeed intake, may have a particularly important effect on production in the longer term,especially if animals are continually being offered unfamiliar feeds.
Reduction of feed neophobia by exposing new feed to animals in their early lives
with mothers or experienced animals
Experience of feeds is essential i f young animals are to develop preferences for themand quickly adapt to eating them in their post -weaning, feeding environment. Livestocksuse their senses (sight, smell, taste and touch) to differentiate among feeds and theylearn about a feed’s sensory characteristics from their mother during the pre -weaningperiod (Provenza and Balph 1987; Provenza 1994, 1995). Thus, mothers can train theiryoung to avoid harmful feeds, and to select nutritious novel alternatives (Mirza andProvenza 1994). Learning in t he absence of a mother or other social teacher may beslower and less effective.
Learning from mother is also very important component of learning to establish a feed preference early in life (Mirza and Provenza,1994; Provenza, 1996; Tien et al.,1999). Therefore, the appropriateness of the mother is considered as a special model forher young to learn about feed because they are genetically related and hence shouldrespond more similarly to smell, tastes and post -ingestive feedback of feed thanunrelated individuals (Chapple and Lynch, 1986). Moreover, the mother might alsoinfluence her young in more subtle ways, for instance, odors and tastes from feeds maybe transmitted through the mother’s milk and subsequently influence diet selection byher young (Galef, 1976). However, there is no study to test this possibility.
In our studies, we suggested that the time taken for weaned animals (both ruminants and monogastrics) to accept and begin to ingest a new feed could depend onwhether the feed is familiar, and familiarity may result from personal experience orlearning from social models such as mother. In these studies, we found that exoticanimals such as the Large White pig and the indigenous goat are two kinds of livestockthat do not like to eat novel feeds (e.g. agro -byproducts). Therefore, from 1998 up tillnow, we have been carrying out studies on feeding behavior in both such species,funded by SAREC and IFS, Swedish institutions. Our main expected outputs from theseprojects are the tactical uses of mothers to train their offsprings either in utero or in thepre-weaning period. These tactics may increase intake and shorten the adaptation timesfor animals to accept novel feeds after they are weaned. In application, the findings m aypave the way for the use of non -conventional feeds from agro -byproducts for livestockproduction in Vietnam and other countries.
In the second experiment on the goats in ‘learning from mother’ and ‘learning from experienced adults’ groups wer e trained for only one week before weaning and thenwere not exposed to rice straw or rice bran until the start of testing at 6 months of age.
During this training, the young goats saw their mother or other adult goats near to themingesting rice straw and rice bran. Then at about 6 months of age, goats in those groupswere tested in the absence of trainers, mother or experienced adults. The goats in bothgroups started to eat those supplements in the first day of the test and reached intakesof 53 g rice straw and 98 g rice bran in 15 min -test by day 7. While, control animals didnot train before weaning (the traditional practice) or at any time after weaning up to thecommencement of testing. Those animals ate no rice straw over the 7 - day test andsmall amount of rice bran on the day 5.
We also tested the effects of sows in training their offsprings, sows of both breeds of Large White and Mong Cai and their 3 -week-old offspring were given duckweed,novel feed to eat each day for 2 weeks. Another group of mothers and offspring were notexposed to such supplement and offspring of both groups were then tested to determinetheir familiarity with duckweed. We found that both breeds accepted duckweed morereadily if they had been exposed to duckweed wi th their mothers in the pre -weaningphase, but Large White offsprings (exotic pig) were slower to accept and ingestduckweed than Mong Cai offsprings (native one). We could conclude that learning frommother is dynamic learning and animals in different gen otype (in the case of Large Whiteand Mong Cai) reared in the same feed environment were exhibited different dietaryhabits.
Feed familiarity and reduction of feed neophobia by pre -natal exposure of the new
feed: learning about feed in utero period
The study was conducted to determine whether fetal experience of mother’s diet , orexposure of her piglets to a feed such as duckweed via cues transmitted in milk, or byobservation after birth but before weaning, influences their post -weaning acceptanceand intake of that feed. The study was done with both native (Mong Cai) and exotic(Large White) breeds of pig.
In the first experiment, offspring of Large White and Mong Cai breeds of sows that wereeither never exposed to duckweed, or were exposed daily to duckweed throughoutpregnancy, were tested after weaning to determine their rate of acceptance and intake ofduckweed in 15-min tests each day for 4 weeks. In these tests, Mong Cai offspringaccepted and ingested duckweed more readily than Large White (exo tic genotype)offspring irrespective of whether their mothers had been exposed to duckweed.
However, the Large White offspring more readily accepted and ingested duckweed iftheir mothers had been exposed to duckweed during pregnancy, whereas Mong Cai(native genotype) offspring did not appear to be influenced by learning in utero. In thisexperiment, so-called ‘learning in utero’, we suggested that when a pregnant mother(Large White pig) was given a supplementary feed (duckweed) the flavor of that feed, o ra metabolite, might be transferred to her fetuses. Probably it promoted the offsprings’familiarity with the feed and reduced their neophobia when confronted with duckweedafter weaning (at three months of age), enabling them to more quickly begin to ing estsuch feed and increase their intake in the short term. The indigenous Mong Cai pigs, incontrast, appeared to exhibit less neophobia and therefore to be less affected by trainingin utero than the exotic Large White breed. To the best of our knowledge , this is the firstevidence that such learning in utero occurs.
A number of questions arise from this study: (i) Is learning more effective in the Large White pig in the first or second or third trimester of pregnancy? (ii) In the case ofthe F1 and F2 of the Large White (LW) and Mong Cai (MC) breeds, does pre -nataltraining of the fetus (by feeding the sow on duckweed during pregnancy) affect thepiglets’ acceptance of duckweed when it is offered to the piglets for the first time afterweaning? These tests will have important practical farm application because crossbreed(F1 and F2 of LW X MC) pigs represent 80 percent of the total pig production populationin Vietnam. The findings from this project will be combined with the previous results o four studies to formulate practical management tactics for training livestock to quickadapt to locally available feed resources. Rapid adaptation reduces the amount of lostproduction when livestock are frequently subjected to changes in their diet. We e xpectthat all of this work will then be incorporated into a guidebook entitled “Tactics forTraining Farm Livestock to Adapt Quickly to Novel Feeds from Locally Available FeedResources”. This book will be targeted to Vietnamese farmers and similar produc ers inother Asian countries.
Opportunity for further research
1. There may be a sensitive period during pregnancy when the fetus learns more effectively about feeds that its mother ingests than at ot her times during pregnancy.
Animals will be given access to duckweed in the first, second or third trimester ofpregnancy and their offsrping will be tested after weaning to determine the exposurehas altered their neophobia or acceptance of duckweed. The output will be confirmation of our previous study and additional information defining the mostsensitive period for transmission of food cues in utero. The experiment will alsoprovide information about the acceptability of this new feed source.
2. There may be differences in the ranking of in utero transmission of cues about feeds in different breeds or crossbreeds. The experiment will be undertaken with F1 and F2genotypes of animals and the output will be a ranking of the different genotypesaccording to how much their preference for feeds i s affected by their experiences inutero.
3. Information about feeds eaten by the animals before she gives birth to the young ones that we believe is transferred to the fetus in utero could alternatively have beenpassed via milk to the piglets in the first days after parturition. T o test this possibility,animals will be left with their own mother after birth, or cross -fostered to other sowsthat have not received duckweed during the last week of pregnancy. The output willbe exclusion or otherwise of the po ssibility that transmission of information frommother to offspring that seems to occur in utero does not, in fact, occur in the periodjust after birth.
4. Transmission of information from mother to her offspring while it is suckling, demonstrated in the previous project, probably occurs via the milk, but might also betransferred in other ways. For example, the offspring may experience odor of feedsthat the mother has ingested before the offspring was re -united with the mother toallow it to suckle. To exc lude this possibility, young animals will be raised from birthon milk produced by mothers that have, or not have, been ingesting duckweed intheir diet. After weaning, the young pig will be tested for their neophobia orwillingness to ingest duckweed. The output will be better information on the relativeimportance of transmission of feed cues via the milk, via skin or body odor, or via, forexample, residual feed near the mother’s mouth.
The other study was conducted to evalu ate whether the experienced animals (exotic Large White and native Mong Cai genotypes) that were familiar with duckweedthroughout pregnancy and gained experiences of eating such feed in utero might begeneralized to other green feed (i.e. legume tree leaf, Leucaena Leucocephala). Theexperiment demonstrated that all experienced pigs with duckweed in both exotic LargeWhite and native Mong Cai commenced ingesting Leucaena Leucocephala feedimmediately in the first day offered it to them. While, the control animals in both suc hgenotypes totally reject that new feed and did not ingest any supplement over the test.
The study also indicated that the flavor of previous feed seems to be moregeneralization to other feed in exotic pig genotype than native one. We recommendedthat such legume tree leaf could be used as a supplementary feed for monogastricanimals. Growing more legume tree also contributes to make a shadow for pasture andimprove the soils in the region.
Improvement of growth race by local byproduct supplement
Phanrang region, Ninh Thuan province is the semi -arid zone of Vietnam and sparse availability of green roughage. However, sheep are widely raised in such area.
Large animals such as cattle and buffalo usually overgraze the natural grassland whileduring the dry season from April to June there is a little growth of grass. In addition, inthe villages of central Vietnam it is traditional practice to confine sheep during the night without access to feed. Supplementary feed, if properly selected by the vil lagers and ifaccepted by the sheep, would enhance sheep production. Commonly available localproducts have potential to be used as supplementary feed. A candidate supplement isprickly-pear cactus (Opuntia elator) especially as emergency feed in the dry s easonwhen growth rate of cactus is higher than the raining season (Tien et al 1994). InPhanrang, Ninh Thuan this cactus is ubiquitous and has no commercial use for anypurpose (Tien 1997).
The objective of this was to determine the value of p rickly-pear cactus as dietary supplement for sheep. Because the cactus is low in protein it was mixed with eithergroundnut cake or fish sauce by -product before offering to the sheep. The two protein -rich feedstaffs are readily available in the study area. It was anticipated that thisinvestigation could contribute to identification of effective, local feed supplements and tothe formation of feeding advice to the smallholder farmers.
The study was conducted in the region with the use of the loc al products prickly- pear cactus, groundnut cake, fish sauce by -product, molasses, rice bran and cassavaflour, two supplements were prepared. The level of cactus in the two supplements was670 g/kg. The cactus is burned to remove spines, chopped and sundri ed before use.
The cactus preparation contained only 12 g crude protein/Kg (68 g/kg dry matter). Witheither groundnut cake or fish sauce by -product the protein content of the supplementswas raised. Sheep that were grazing during the day were either offer ed no supplementor one of the supplements when confined during the night. During a period of threemonths from 4 to 6, non -supplemented, control sheep gained 98 ± 10.50 g/day. Sheepsupplemented with cactus and groundnut gained 145 ± 12.31 g/day, and those givencactus and fish sauce gained 130 ± 5.75 g/day. The increase in weight gain whensupplemented is explained by supplying more essential nutrients for both rumenorganisms to develop and bypass ones to promote growth in supplemented sheep.
General conclusion
 When livestocks especially ruminants and exotic monogastrics are offered an unfamiliar feed, feed neophobia will occurs and delays its acceptance and intakemay be sub-optimal for periods of a week or more.
 The conjunction of familiar odors or flavors of native grasses with an unfamiliar feed will increase feed recognition and its rate of acceptance and shorten the intervalbetween first exposure and first ingestion. The overall result will be that animalsmaintain a higher average feed intake under conditions in which feeds are frequentlychanged and are unfamiliar.
 Exposing young livestocks to feedstuffs in the presence of their mother or another experienced adult reduces their neophobia when diets are changed suddenly toinclude one of these feedstuffs. The overall effect is to reduce the period of sub -optimal intake when diets are changed and to increase production in the interimperiod.
 Transmission of diet flavor from a mother to her offspring via milk is an important component of learning from mother. Learning by observation of mother ingestingfoods (and having the opportunity to mimic the activity) together with learning via cues in mother’s milk establishes a food preference for livestock that helps them toadjust to their food environ ment after weaning.
 Young animals can learn about a feed in utero or by a combination of the effects of suckling and social interactions when their mother ingests that food in the post -natal,pre-weaning period, and so be more familiar with that food when they first encounterit in the post-weaning period.
 Animals have more readily ingest un -conventional supplement, with association with either its flavor or type of feed in utero, such previous condition by animals maygeneralize to other green feed.
 Goat is a effective browser animal by the use of it’s bipedal stance behavior for making ‘over head foraging’ ability to access either feed sources and ingest morebiomass in the forest or supplement in the case of putting the feed source at a heightof higher ground basic level.
 Prickly-pear cactus (Opuntia elator) could be used as an emergency feed in the dry season for ruminants and it could be in use more effective when cactus supplementsto the livestocks in combining with either groundnut cake or fish s auce by-product.
In short, the studies would provide new results to develop management tactics for overcoming feed neophobia and promoting feed acceptance and higher intake. Thosetactics will be the basis for recommendations leading to more appr opriate techniques forutilizing agro-byproducts as supplements for livestocks in Vietnam and will pave the wayto improving animal productivity and increasing income of poor farmers. More effectiveuse of agro-industrial products will also assist in pro tecting the environment.
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Tien. D. V. 2001a. Manipulation of fee ding behavior of livestocks for improving production: matching feeding behavior of small ruminants to agro -byproductsresources in hilly and mountainous areas of Vietnam. Proceeding of SIDAconference at Hat Yai, Thailand November. 2001.
Tien. D. V. 2001b. The contribution of matching animal behavior to locally available feed resources to sustainable livestock production and changing farmer behaves insuch system in the central part of Vietnam. Synthesis paper contributed to FAO ofElectronic Conference of AWI.
Tien, D. V., Beynen, A., Nolan, J. V., and Preston, T.R. 2002a Pre - and post- natal exposure to duckweed affects its post -weaning familiarity and intake in LargeWhite and Mong Cai pigs. Asian Australasian Journal of Animal Science(submitted).
Tien, D. V., Beynen, A., and Nolan, J. V. 2002b Effects of experience in the pre - weaning period on food familiarity and intake in goats: transmission of preferencefor rice straw via mother’s milk or by social transmission. Small RuminantResearch (submitted).
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