Induced lactation in cows and heifers by short-term treatment with steroid hormones

Abstract

Summary. Induction of lactation following administration of estradiol-17 and progesterone for 7 consecutive days was investigated in heifers and non-lactating multiparous cows of the Friesian breed. Lactation started 14 days after the end of the treatment with steroids.Mean milk yields for 32 induced lactations were between 2 000 and 3 000 kg/300 days except for two heifers which failed to respond to the treatment (50 kg/120 days and 650 kg/ 150 days, respectively). Mean milk yield for the multiparous cows was 80 p. 100 of that produced during previous natural lactations whereas heifers produced only 60 p. 100 of milk yield recorded during natural lactations which followed the induced lactation. Milk yields during 21 induced lactations in cows and heifers and during natural lactations in the same animals were correlated (r = !-0.47, P < 0.05).Plasma concentrations of total estrogens, progesterone and prolactin revealed that mammary gland growth and lactogenesis occurred when steroid concentrations had decreased and prolactin had increased. Additional treatment with hydrocortisone acetate for 3 days, coincident with the time milking began, had a positive effect on subsequent milk yields (P < : 0.001). ).Increasing the amounts of estradiol-17 and progesterone injected did not result in greater milk yields but did result in an increase in the post-treatment frequency of cystic follicles.Ten cows and 13 heifers were inseminated during the induced lactation. One cow and one heifer failed to conceive, two heifers conceived but subsequently aborted, and the other cows and heifers conceiving showed normal pregnancy, parturition and lactation.

Hormone levels in plasma of ewes induced into lactation

“…Quartic regressions (not shown) revealed that the increases in the concentrations of TE and P 4 were essentially the same as in dairy cows receiving E 2 -0 and P 4 to induce lactation (Charkiyarat et al, 1978 ;Delouis et al, 1978), but that the magnitude of those increases in ewes was equivalent to a five-fold increase in the hormone dose injected per kg of body weight. Plasma TE and P 4 levels returned to preinjection concentrations by the day milking began.…”

“…Although milk yields increased rapidly, they were still less than those of ewes lactating after lambing, and the number of ewes which lactated after treatment was variable. The ewes were also induced to lactate after injections of estradiol-17(3 (E 2 -(3) and P 4 at doses (0.5 and 1.25 mg/kg body weight/day, respectively) similar to (D'Amico et al, 1976 ;Alifakiotis et al, 1980) or five-fold higher (Head et al, 1980) than those used to induce cows into lactation (Smith and Schanbacher, 1973 ;Erb et al, 1976 ;Chakriyarat et al, 1978 ;Delouis et al, 1978). In these studies, the milk yields of induced ewes were less than after lambing, and the number of animals responding to the treatment varied.…”

Induction hormonale de la lactation chez la vache : résultats de trois années d'expérimentation en ferme

“…Les C'est pour tenter de normaliser la sécrétion de prolactine au niveau hypophysaire que les animaux reçoivent un traitement complémentaire par la réserpine (COLLIER et al , 1976 ;B AUMAN et al , 1977 ;PEEL et al , 1979 ;J OHKE et al , 1980 Bien que la sécrétion de prolactine présente des variations saisonnières importantes chez la Vache (P ETERS et al, 1981), les injections de réserpine pendant toute la durée des essais n'ont pas permis de supprimer les effets de la saison sur les productions laitières totales. Ces dernières sont plus élevées lorsque la durée d'éclairement quotidien augmente, c'est-à-dire quand la prolactinémie s'élève pendant la lactation normale (P ETERS et al , 1978) et la lactation après induction hormonale (K ESS tNGEx et al , 1979 Les hormones naturelles, utilisées pour induire la lactation (oestradiol 17 (3 et progestérone) s'éliminent très rapidement après l'arrêt du traitement (D ELOUIS et al, 1978). Les concentrations des oestrogènes totaux dans le lait produit par les vaches après vélage et après induction sont tout à fait comparables ; celles de progestérone sont plus élevées pendant les 5 premiers jours qui suivent l'induction qu'après le vélage, cette différence disparaît en 10 jours (N ARENDRAN et al, 1979 …”

<b>Eficácia do tratamento com antibiótico injetável associado a selante de tetos sobre a saúde do úbere de novilhas com lactações induzidas</b>

“…As mudanças fisiológicas e hormonais que ocorrem no período entre o terço final da gestação e o parto são essenciais para o início e manutenção da síntese e produção de leite da próxima lactação (AKERS, 2006). Assim, com a utilização do PIL é possível induzir à lactação em vacas e novilhas que estavam secas (não lactantes) e não gestantes (DELOUIS et al, 1978;MUHAMMAD et al, 2016). Entretanto, como condição essencial para sucesso do PIL, as vacas e novilhas devem estar clinicamente saudáveis, possuir bom escore de condição corporal (ECC), apresentar mérito genético para produção de leite e não estar gestante, embora possam apresentar problemas reprodutivos (anestro, repetição de cio, etc -LAKHANI et al, 2017;JEWEL,2002 1975).…”

“…De acordo com esses estudos, o leite de vaca e novilhas com lactações induzidas podem apresentar um valor econômico maior por unidade de leite produzido, devido ao maior teor de sólidos (MACRINA; TOZER; KENSINGER, 2011). Vários estudos avaliaram a eficácia reprodutiva de vacas e novilhas após PIL (COLLIER; HAYS, 1975;BALL et al, 2000;HARNESS et al,1978;DELOUIS et al, 1978). Lactações induzidas em vacas quando comparadas as lactações convencionais tiveram 1,25 vs1,32 serviços por concepção, respectivamente.…”