Tsoka ilo, makina oyesera apano ali ndi mavuto akulu. Zina mwa zinthuzi zakhala zikudziwika kwa nthawi yaitali, monga kuti kuyezetsa n’kokwera mtengo kwambiri kapena kumavulaza kapena kupha nyama zambiri. Kuphatikiza apo, vuto lalikulu ndilakuti kuyesa sikugwira ntchito momwe asayansi angafune.
Asayansi akamaphunzira za mankhwala, amayesa kuona ngati n’kotetezeka kuti munthu akumane ndi kachinthu kakang’ono ka mankhwalawo kwa zaka zambiri. Asayansi akuyesera kuyankha funso la chitetezo cha nthawi yayitali kukhudzana ndi chinthu chochepa. Koma kuphunzira zotsatira za nthawi yaitali pa zinyama ndizovuta chifukwa nyama zambiri sizikhala ndi moyo wautali, ndipo asayansi amafuna chidziwitso mofulumira kuposa moyo wachilengedwe wa nyama. Chotero asayansi amavumbula nyama ku mlingo wokulirapo wa mankhwala—chiŵerengero chapamwamba m’zoyesera kaŵirikaŵiri chimasonyeza zizindikiro za kumwa mopambanitsa.
Ndipotu ochita kafukufuku angagwiritse ntchito milingo ya mankhwalawo yomwe ndi yochuluka kuwirikiza masauzande ambiri kuposa imene munthu aliyense angakumane nayo akaigwiritsa ntchito. Vuto ndiloti ndi njira iyi, zotsatira zake siziwoneka nthawi zikwi zambiri mofulumira. Zonse zomwe mungaphunzire kuchokera pakuyesa kwa mlingo waukulu ndi zomwe zingachitike muzochitika za overdose.
Vuto lina loyesa nyama ndi loti anthu si makoswe akuluakulu, mbewa, akalulu, kapena nyama zina zoyesera. Zoonadi, pali zofanana zazikulu mu biology, maselo, ndi machitidwe a ziwalo, koma palinso kusiyana komwe kumapangitsa kusiyana kwakukulu.
Zinthu zinayi zazikuluzikulu zimathandizira kudziwa momwe kuwonekera kwa mankhwala kumakhudzira chiweto: momwe mankhwalawo amatengedwera, amagawidwa m'thupi lonse, amapangidwa ndi metabolized ndi excreted. Njirazi zimatha kusiyanasiyana pakati pa zamoyo, nthawi zina zomwe zimapangitsa kuti pakhale kusiyana kwakukulu kwa zotsatira za kukhudzana ndi mankhwala.
Ofufuza akuyesa kugwiritsa ntchito nyama zomwe zili pafupi ndi anthu. Ngati akuda nkhawa ndi zomwe zingakhudze mtima, angagwiritse ntchito galu kapena nkhumba - chifukwa kayendedwe ka kayendedwe ka zinyamazi ndi ofanana kwambiri ndi anthu kusiyana ndi nyama zina. Ngati ali ndi nkhawa ndi dongosolo lamanjenje, amatha kugwiritsa ntchito amphaka kapena anyani. Koma ngakhale mutakhala wofanana bwino, kusiyana pakati pa zamoyo kungapangitse kukhala kovuta kumasulira zotsatira za anthu. Kusiyana kochepa mu biology kungapangitse kusiyana kwakukulu. Mwachitsanzo, mu makoswe, mbewa ndi akalulu, khungu limatenga mankhwala mwamsanga - mofulumira kuposa khungu la munthu. Motero, kuyesa pogwiritsa ntchito nyama zimenezi kungasonyeze kuopsa kwa mankhwala amene amamwa pakhungu.
Malingana ndi US Food and Drug Administration, oposa 90% a mankhwala atsopano omwe amalonjeza amalephera kuyesedwa kwa anthu, mwina chifukwa chakuti mankhwalawo sagwira ntchito kapena chifukwa amayambitsa mavuto ambiri. Komabe, chilichonse mwazinthuzi chidayesedwa bwino m'mayesero ambiri anyama.
Kuyezetsa nyama kumatenga nthawi komanso ndalama zambiri. Zimatenga pafupifupi zaka 10 ndi $3,000,000 kuti amalize maphunziro onse a nyama zofunika kulembetsa mankhwala amodzi ku US Environmental Protection Agency. Ndipo kuyesa kwa mankhwala amodzi okhawo kupha nyama zokwana 10 - mbewa, makoswe, akalulu, mbira ndi agalu. Pali mankhwala masauzande ambiri omwe akuyembekezera kuyesedwa padziko lonse lapansi, ndipo kuyesa kulikonse kungawononge mamiliyoni a madola, zaka zantchito, ndi moyo wa nyama masauzande. Komabe, mayeserowa si chitsimikizo cha chitetezo. Monga tanenera pamwambapa, zosakwana 000% za mankhwala atsopano omwe angakhalepo amapambana mayesero aumunthu. Malinga ndi nkhani ya m’magazini a Forbes, makampani opanga mankhwala amawononga avareji ya $10 biliyoni kupanga mankhwala atsopano. Ngati mankhwalawa sagwira ntchito, makampani amangotaya ndalama.
Ngakhale kuti mafakitale ambiri akupitirizabe kudalira kuyesa kwa zinyama, opanga ambiri akukumana ndi malamulo atsopano omwe amaletsa kuyesa zinthu zina pa zinyama. European Union, India, Israel, São Paulo, Brazil, South Korea, New Zealand, ndi Turkey atengera zoletsa kuyesa nyama ndi/kapena zoletsa kugulitsa zodzoladzola zoyesedwa. Dziko la UK laletsa kuyesa kwa ziweto pamankhwala am'nyumba (monga kuyeretsa ndi kuchapa zovala, zotsitsimutsa mpweya). M'tsogolomu, mayiko ambiri atenga ziletsozi chifukwa anthu ochulukirachulukira akukana kuyesa mankhwala pa nyama.