Forfatterne skisserer strategier for å begrense tap ved å øke drektighetsprosenten og redusere det tidlige kalvetapet.

Caribou (Rangifer tarandus) have been used as an example of a polygynous species in which one could expect females to manipulate their investments in sons and daughters based on their physical condition. We investigated whether the effect of maternal condition, measured as female body mass, on preweaning maternal care measured as calf mass in mid-July, calf mass in mid-November and calf mass gain (growth between mid-July and mid-November), was sex-biased in reindeer. We analysed separately young (≤ 4 years), prime age (5–10 years) and old (>10 years) mothers. Consistently, preweaning maternal care increased with increasing mother quality, but maternal condition did not influence whether a female produced a son or a daughter. Moreover, regardless of whether a female was young, prime age or old, there was no conclusive evidence of female quality-related, sex-biased preweaning maternal care in the study population. Our results indicate that maternal expenditure may be of equal magnitude in male and female offspring, regardless of the mothers' physical condition, and may support the hypothesis that a high level of maternal expenditure limits sex-biased maternal care.

Different evolutionary hypotheses have been proposed to explain variation in offspring sex ratios among mammalian populations. The Trivers and Willard and local resource competition hypotheses, which are based on adaptive modification by maternal investment, are two opposing hypotheses commonly used for ungulates, but empirical patterns often do not fit either hypotheses' expectations. We investigated sex ratio variation in 1658 reindeer (Rangifer tarandus) calves in relation to their mothers' mass and age, while accounting for potential density-independent factors such as climate. The most parsimonious model included only the effect of maternal age, the proportion of males increasing with increasing maternal age. Similar models in terms of parsimony included (in addition to maternal age) the winter temperature or the North Atlantic Oscillation (NAO) index when the mothers were in utero, indicating that climatic conditions experienced by mothers in their year of birth, have the potential to influence variation in a cohort's offspring sex ratio. Thus, a combination of both density-dependent and density-independent factors may influence sex ratio variation in reindeer and perhaps in other ungulates. We suggest that, if an adaptive maternal strategy is present, it may be induced and/or inhibited by, or interact with other factors such as climate.

Age-specific rates of survival and reproduction in iteroparous organisms remain a key issue in population ecology. How patterns of survival vary with age in large herbivores is well known; much less is known regarding age-specific patterns of reproduction. The senescence hypothesis predicts a progressive loss of function accompanied by decreased performance with age. The terminal investment hypothesis predicts that the proportion of resources a mother invests (i.e. effort relative to costs) is expected to increase toward the end of her life-span, when the number of offspring she can expect to rear in the future is low. Assuming that the costs remain stable, the terminal investment hypothesis predicts increased reproductive effort with age. We used data on body weight of 1,956 semi-domestic reindeer (Rangifer tarandus) calves from females with known age and weight to test these two (not mutually exclusive) hypotheses. Body weight of calves clearly decreased after 7 years of age was reached (also after controlling for female body weight), which was in support of the senescence hypothesis. We can conclude that either the terminal investment hypothesis is wrong, and/or the reproductive costs increase with age in female reindeer.

Theory suggests that a male in good condition at the end of the period of parental investment will outproduce a sister in similar condition, while she will outproduce him if both are in poor condition. Accordingly, natural selection should favor parental ability to adjust the sex ratio of offspring produced according to parental ability to invest. As maternal condition declines from good to poor, the fetal sex ratio should decline from a high proportion of males to a high proportion of females. Data from 1525 domestic reindeer (Rangifer tarandus) in six different herds slaughtered during December and January in 1976 through 1979 do not support a relationship between the sex of the fetus and either the condition of the mother or her age.

In September 1990, a total of 69 calves with a minimum body weight of 46 kg were allocated into two groups, one treated with a single injection of 75 mg medroxyprogesterone acetate (N = 35), the other serving as control (N=34). Blood samples were collected for progesterone analysis in December 1990 and 1991. Udder palpation was performed in July and September 1990. Treated animals had significantly lower plasma progesterone levels in December 1990. The pregnancy rate as determined by udder palpation was 16.7% for treated animals and 48.3% for controls (P<0.01). All animals which were found to be pregnant had high progesterone levels (>5 ng/ml) the following winter. The mean body weight increase was 5.1 kg lower in females which kept their calves until September than in barren females (P<0.05). More than 50% of the pregnant females lost their calves during the summer.

Da strukturerings- og optimaliseringsprosessen innen reindriften skjøt fart i Trøndelag, - i 1976-77 som følge av reindriftsavtalen -, hadde man felles startgrop med Finnmark, - en kjøttproduksjon på 10-12 kg pr. rein i vårflokken. Utviklingen etter 1976-77 har tatt ulike løp. Dette skyldes ikke rovdyr eller andre naturgitte forhold. Det bør derfor være mulig å snu trenden innen Finnmark ved i noen grad å følge de strategier og faglige opplegg som har vært grunnleggende for utviklingen i sør. Klarhet i sør og mangel på klarhet i nord med hensyn til rammebetingelsene for reindriftsutøvelsen (reintall og antall driftsenheter innen distriktene samt høgste reintall pr. driftsenhet) er kanskje den mest fundamentale forskjell mellom områdene.

Reinen lever i et svært sårbart miljø, hvor små inngrep kan gi uante følger på lengre sikt. Innføring av medikamentbruk i en næring som tradisjonelt har klart seg uten medfører derfor et betydelig ansvar. For eksempel vil bruk av ivermectin på flokker fra dårlige, overbelastede beiter sannsynligvis gi bra effekt, men samtidig kan det bidra til å kamuflere problemer som kunne løses på annen måte, f.eks. ved omlegging av flokkstruktur og slakteuttak. Imidlertid vil bruk av ivermectin i reinflokker som lever under normalt gode betingelser kunne gi et resultat i form av økt kjøttavkastning som gjør at et evt. rutinemessig behandlingsopplegg vil kunne være økonomisk fordelaktig.

I en administrativ og forvaltningsmessig sammenheng er det fortsatt all grunn til &aring; beholde "antall rein i v&aring;rflokken" som referanse og dimensjoneringsbegrep for reinflokkene. Det samme gjelder bruken av "kg kj&oslash;tt pr. rein i v&aring;rflokken" som m&aring;leenhet og sammenligningsgrunnlag for effektiviteten i reinkj&oslash;ttproduksjonen. &Aring; referere til VBE, - ved angivelse av beitekapasitet, eller som "antall VBE i v&aring;rflokken", har fordeler i sammenheng med veiledning, undervisning og forskning.

Reindriften, og dermed også reinens utnyttelse av det totale årsbeitepotensial, er i aller videste forstand innrettet mot selektiv bruk av beiteområdene og beitevegetasjonen. Dette er en tradisjon som tamreindriften har fra villrein og som det er all grunn til å utvikle videre i en tamreinsammenheng. Det primære seleksjonsnivå ligger i villreinens trekk mellom sesongbeiteområder, eller flyttingene med tamrein mellom vår-, sommer-, høst- og vinterbeiteområder. Her har en forsøkt å framholde høstbeiteområdet spesielt. En har tidligere hatt en tendens til å glemme bort dette areal i alle andre betraktninger om kalvingsland, flytteleier, vår- og vinterland.

Three trials with treatment of reindeer warbles are carried out. All treated groups were injected intramuscularly with Warbex (35%, American Cyanamid), dosage 10 mg active ingredient/10 kg live weight. In total 911 calves and 403 adult females were included in the experiments. All animals were individually marked with plastic eartags. The trials tried to give answers as to the effect of treatment on: a) weight development during winter, b) weight development to the normal age of slaughter (18 months) and c) loss rate during winter. One trial deals with the effect of weight loss during winter by different date of treatment. All studies are undertaken within sex. Generelly the trials show that treated animals lost more weight during winter than untreated. There was found significant higher weight loss for treated female calves (0.7 kg, p=0.005) in the period January 13. — April 28. in trial I and for male calves (0.8 kg, p=0.01) in the period February 14. — April 4. in trial II. There is a trend that treatment increases the slaughter weight. A significant higher increase in the slaughter weight (0.8 kg, p=0.05) of treated male calves was found in trial III. No effect was found by treatment in the loss of animals in winter. The calves lossed during winter had a significant lower live weight at the start of the trial compared to those which survived. In the period February 14. — April 4. there was a higher weight loss in the male calves which were treated on February 14. compared to those treated on November 27. (0.5 kg, p=0.01). Forsøk med behandling av reinkalver mot reinbremslarver (Oedemagena tarandi L og Cephenemyia trompe L). Effekt på kalvens kondisjon målt ved levende vekt og overlevingsevne. Abstract in Norwegian / Sammendrag: Det er utført tre forsøk med behandling av rein mot reinbremselarver (Oedemagena tarandi L.) og Cephenemyia trompe L.). I alle forsøk er brukt intramuskulær injeksjon av Warbex (Am. Cyanamid) 35% med dosering 30 mg aktivt stoff pr. 10 kg levende vekt. I alt inngår 911 kalver og 403 voksne simler i forsøkene. Forsøkene har søkt å gi svar på mulige effekter av nevnte behandling på a) vektutvikling om vinteren, b) vektutvikling frem til normalt slaktetidspunkt (18 mndr.),c) tap av dyr om vinteren. Videre er det søkt å gi svar på om behandlingstidspunktet (27/11 og 14/2) har betydning for vekttapet om vinteren, alle undersøkelser er gjort innen kjønn. Generelt viser forsøkene at behandlede dyr tar av mer i vekt om vinteren enn ubehandlede dyr. Det ble funnet signifikant større vekttap for behandlede simlekalver (0.7 kg, p=0.005) i tidsrommet 13/1—28/4 i forsøk I og for behandlede bukkekalver (0.8 kg, p=0.01) i tidsrommet 14/2—4/4 i forsøk II. Det er også en tendens til at behandlingen virker til å øke slaktevekten. Det ble således funnet signifikant høyere økning i slaktevekt (0.8 kg, p=0.05) for behandlede bukker i forsøk III. Det ble ikke påvist effekt av behandlingen på tap av dyr om vinteren. De kalvene som ble borte om vinteren hadde signifikant lavere vekt ved forsøkets start sammenlignet med de som overlevde. I perioden 14/2—4/4 ble det funnet større vekttap hos de bukkekalver som ble behandlet 14/2 sammenlignet med behandling 27/11 (0.5 kg, p=0.01). Koikelu poronvasojen hoitamiseksi poropaarmantoukkia vastaan. Vaikutus vasojen kuntoon mittana elopaino ja henkiinjååmiskyky. Abstract in Finnish / Yhteenveto: Suoritettiin kolme koetta porossa loisina esiintyvien kurmunja saulakantoukkien (Oedemagena tarandi L ja Cephenemyia trompe L) torjumiseksi. Kokeissa kåytetiin Warbex-35%:sta valmistetta ruiskeena lihakseen, annoksen suuruus oli 30 mg vaikuttavaa ainetta 10 elopainokiloa kohti. Kaikkiaan kokeissa kåsiteltiin 911 vasaa ja 403 vaadinta. Kokeissa selviteltiin kåsittelyn mahdollisia seurausvaikutuksia a) talven aikaiseen painonkehitykseen b) painonkehitykseen normaaliin teurastusajankohtaan saakka (18 kk) c) elainten talviaikaiseen katoon. Lisåksi pyrittiin vielå selvittåmåån onko kåsittelyajankohdalla (27.11. ja 14.2.) merkitystå porork talvella tapahtuvaan painonalenemiseen. Kokeet tehtiin samaa sukupuolta olevilla elåimillå. Yleisesti kokeet osoittavat, ettå kåsiteltyjen elainten paino våhenee talvella enemmån kuin kåsittelemåttomien elainten paino. Koe I osoitti, etta kåsiteltyjen naarasvasojen paino aleni merkittåvåsti (0.7 kg, p=0.005) 13.1.—28.4. vålisenå aikana, samoin kokeessa II kåsiteltyjen urovasojen (0.8 kg, p=0.01) 14.2—4.4. vålisenå aikana. Kåsittely nåyttåå myos kohottavan teuraspainoa. Kokeessa III havaittiin kåsitellyillå uroksilla merkittåvån korkea teuraspainon lisååntyminen (0.8 kg, p=0.05). Kasittelyn mahdollista vaikutusta porojen menehtymiseen talvella ei voitu osoittaa. Ne vasat, joita ei talvella tavattu, olivat jo kokeen alkaessa huomattavasti keveåmpiå kuin ne vasat, jotka såilyivåt yli talven. 14.2. kåsitellyt urovasat menettivat 14.2.—4.4. vålisenå aikana enemmån painoa kuin 27.11. kåsitellyt (0.5 kg, p=0.01).