Induced lactation in pubertal heifers: Efficacy, response to bovine somatotropin, and profitability

Abstract

Heifer rearing represents one of the largest costs of commercial dairying because these animals do not begin to produce milk until approximately 2 yr of age. The objectives of this study were to characterize milk production, growth, reproduction, and herd life after induced lactation in healthy 15-mo-old heifers. We further wanted to quantify their lactation response to bovine somatotropin (bST), and compare survival rate and profitability of heifers induced into lactation to that of heifers reared using traditional methods. Holstein heifers (n = 32) were induced into lactation by administration of estradiol-17β (0.075 mg/kg of body weight per d) and progesterone (0.25 mg/kg of body weight per d) for 7 d. Milking began on experimental d 18. Heifers were paired based on milk production, and one in each pair was assigned randomly to bST or control treatment groups; treatments began on 25 ± 7 d of lactation, and milk production was compared for 70 d. Heifers treated with bST produced 14.7% more milk than did controls. After the 70-d comparison period, all heifers received bST for the remainder of their lactations. Throughout the induced lactation, heifers gained 0.69 kg/d, averaged 1.8 services/pregnancy, and 27 heifers calved for a second lactation. For the herd life and economic analyses, heifers induced into lactation were compared with similarly aged heifers in the same herd reared by traditional management methods. The animals induced into lactation had a 62.7% chance of remaining in the herd as long as the peer cohorts, but both groups had similar productive lifespans. Net present value for an induced animal ($2,459) was not different from that of a traditionally raised peer ($3,137). In summary, heifers hormonally induced into lactation with estrogen and progesterone were healthy, grew normally, had a mean daily milk production of 18 kg with normal composition, and had good reproductive performance. Based upon the assumptions and prevailing financial environment of this experiment, hormonally induced lactation of 15-mo-old heifers, as a routine management tool, was not more profitable than traditional management practices.

Effect of mammary stimulation on dairy cows and heifers exposed to a lactation induction protocol

“…The success rates achieved in the current study are similar to those reported in previous studies [13,14]. The success rate for heifers (85%) was less than that (97%) reported previously [15]. The success rate for cows (71%) was somewhat lower than the 90% rate reported by Jewel [14].…”

“…Kensinger [7] found it more profitable to induce lactation in non-breeder cows than to purchase replacement heifers or to cull non-lactating cows. However, Macrina et al [15] found no economic benefit in using lactation induction in heifers. The high fertility of dairy heifers in temperate regions in this last study might have led to the estimation of no beneficial effects of lactation induction.…”

Induced lactation in heifers: Effects of dexamethasone and age at induction on milk yield and composition

“…Lactation can be induced successfully in 15-mo-old dairy heifers; however, they produce less milk than postpartum animals (Smith and Schanbacher, 1974;Macrina et al, 2011b). This is not surprising considering they are much younger than postpartum heifers that calve at 24 to 25 mo of age.…”

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

“…Uma possível explicação pode ser pelo fato de estímulos incompletos provocados por hormônios exógenos injetáveis durante o PIL quando comparado a lactações não induzidas. Com isso é necessário maior período para o desenvolvimento da GM e dos alvéolos até atingir o pico de produção de leite (MELLADO et al, 2011;MACRINA et al, 2014;DELOUIS et al, 1978;HAYS, 1975;TOZER;. É possível observar também que o pico de produção de leite em novilhas é ainda mais lento quando comparado ao de vacas, o que deve se explicar pelas novilhas continuarem seu crescimento após o início da lactação (MAGLIARO et al, 2004;TOZER;.…”

“…No presente estudo, foram observados maiores teores de sólidos do leite (gordura, proteína e lactose) em comparação com resultados de Tozer;.…”