Productive indicator in a Holstein dairy herd: growth and height curves, reproductive and productive traits and genetic parameters

Data on weight, height, productive and reproductive performance of 1,272 Holstein heifers, born from 1990 to 1998, were used to evaluate the growth and height patterns of these females from birth to first calving, and the following traits: weight at first calving (PP), age at first calving (IP), milk production in the first lactation (PL) and first calving interval (IEP), and to estimate genetic parameters of these traits. The von Bertalanffy fitted models were: Yi=802.10 (1-0.630EXP (-0.0022t)) for weight, and Yi=1.40 (1-0.208EXP (-0.0038t)) for height. The average performance of heifers were: height 140cm, weight 602kg and 27 month of age at first calving. The total milk yield was 8,026kg and first IEP was 420 days. The (co)variance components estimates were obtained by a derivative-free algorithm with the DFREML. The estimates of heritabilities were 0.31, 0.35, 0.34, respectively for PP, IP and PL, and 0.10 for IEP. The genetic correlations estimates between PP and PL, PL and IP and IEP and PL were low. The correlation between IEP and PP was 0.49 and between IEP and IP was, -0.69, sugesting an antagonism between the two last traits.Foram analisados dados de peso, altura e desempenho produtivo e reprodutivo de 1.272 novilhas da raça Holandesa, nascidas no período de 1990 a 1998. Estudaram-se o desenvolvimento em peso e altura do nascimento até o primeiro parto, as características peso ao primeiro parto (PP), idade ao primeiro parto (IP), produção de leite na primeira lactação (PL), primeiro intervalo de partos (IEP), e os parâmetros genéticos pertinentes. As equações para as curvas de peso e altura, estimadas pelo modelo proposto por von Bertalanffy, foram: Yi= 802,10 (1 - 0,630EXP (-0,0022t)) e Yi= 1,40 (1 - 0,208EXP (-0,0038t)), respectivamente. As novilhas atingiram o primeiro parto com altura média de 140cm e peso de 602kg aos 27 meses de idade. A produção total de leite na primeira lactação foi de 8.026kg e o primeiro IEP 420 dias. Na obtenção dos componentes de (co)variância utilizou-se o método da máxima verossimilhança restrita livre de derivada. As estimativas de herdabilidade foram 0,31, 0,35 e 0,34, respectivamente, para PP, IP e PL, e 0,10 para IEP, evidenciando variância genética aditiva média para as três primeiras características. As correlações genéticas apresentaram pequena magnitude para PP e PL, PL e IP, e IEP e PL. A correlação entre IEP e PP foi 0,49; entre IEP e IP o valor foi negativo, -0,69, indicando provável antagonismo entre as duas últimas características.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de São Paulo (UNIFESP) Faculdade de Medicina de Ribeirão Preto Departamento de GenéticaUniversidade Estadual Paulista Faculdade de Medicina Veterinária e ZootecniaInstituto de ZootecniaUniversidade de São Paulo Escola Superior de Agricultura Luiz de QueirozUNIFESP, Faculdade de Medicina de Ribeirão Preto Depto. de GenéticaSciEL

Orelha de Elefante Mexicana (Opuntia stricta [Haw.] Haw.) spineless cactus as an option in crossbred dairy cattle diet

new genotype of spineless cactus is being used in the diets of dairy cattle that are raised in semi-arid regions. However, little is known about its nutritional value. This study aimed to evaluate the effects of replacing Miúda (Nopalea cochenillifera Salm Dyck) with Orelha de Elefante Mexicana (Opuntia stricta [Haw.] Haw.) spineless cactus, on nutrient intake and digestibility, milk yield and composition, feeding behaviour, microbial protein synthesis, nitrogen balance, and ruminal and blood parameters of dairy cows. Ten Girolando cows, 500 ± 51.6 kg bodyweight, were distributed in a double Latin square design 5 x 5. The treatments consisted of replacement levels of Miúda (MIU) by Orelha de Elefante Mexicana (OEM) at 0, 25, 50, 75, and 100%. The intake and digestibility of dry matter (DM) (14.38–12.95 kg d-1, 716.3–658.9 g d-1), organic matter (OM) (13.01–11.43 kg d-1, 747.8–704.8 g d-1), crude protein (CP) (2.02–1.61 kg d-1, 863.8–845.2 g d-1) and total digestible nutrients (TDN) (9.38–7.92 kg d-1) decreased linearly with the increase in replacement. Despite the decrease in intake and digestibility, the supply of nutrients was sufficient to maintain a milk yield of 12.5 kg d-1. The average daily weight gain decreased linearly with the increase in replacement, while protein microbial efficiency (g microbial CP kg-1 TDN intake; 91.24 to 127.44 g kg-1) increased linearly. Thus, OEM could replace 100% MIU in diets with 48% of spineless cactus, for crossbred lactating cows with 12.5 kg d-1 milk yield. Therefore, OEM is a viable new option for producing milk in smallholder livestock systems in semi-arid regions.Keywords: Alternative forage, milk yield, ruminal parameter, semi-arid, smallholder livestock syste