ALPHARMA BEEF CATTLE NUTRITION SYMPOSIUM: Implications of nutritional management for beef cow-calf systems1

Abstract

The beef cattle industry relies on the use of high-forage diets to develop replacement females, maintain the cow herd, and sustain stocker operations Forage quantity and quality fluctuate with season and environmental conditions Depending on class and physiological state of the animal, a forage diet may not always meet nutritional requirements, resulting in reduced ADG or BW loss if supplemental nutrients are not provided It is important to understand the consequences of such BW loss and the economics of providing supplementation to the beef production system Periods of limited or insufficient nutrient availability can be followed by periods of compensatory BW gain once dietary conditions improve This may have less impact on breeding animals, provided reproductive efficiency is not compromised, where actual BW is not as important as it is in animals destined for the feedlot A rapidly evolving body of literature is also demonstrating that nutritional status of cows during pregnancy can affect subsequent offspring development and production characteristics later in life The concept of fetal programming is that maternal stimuli during critical periods of fetal development have long-term implications for offspring Depending on timing, magnitude, and duration of nutrient limitation or supplementation, it is possible that early measures in life, such as calf birth BW, may be unaffected, whereas measures later in life, such as weaning BW, carcass characteristics, and reproductive traits, may be influenced This body of research provides compelling evidence of a fetal programming response to maternal nutrition in beef cattle Future competitiveness of the US beef industry will continue to be dependent on the use of high-forage diets to meet the majority of nutrient requirements Consequences of nutrient restriction or supplementation must be considered not only on individual animal performance but also the developing fetus and its subsequent performance throughout life.

Maternal nutrition and programming of offspring energy requirements1

“…Concepts of developmental programming, or the idea that stressors during critical windows of development can have both short- and long-term consequences in offspring, began to emerge about three decades ago based on human epidemiological studies ( Barker, 1992 , 2004 ). Research with animal models, including livestock, has since demonstrated that developmental programming is probably universal and that consequences on offspring growth, development, and health are likely much larger than previously thought ( Wu et al, 2006 ; Caton and Hess, 2010 ; Funston et al, 2012 ; Reynolds and Caton, 2012 ; Greenwood et al, 2017 ; Hoffman et al, 2017 ; Reynolds et al, 2017 ). Maternal stress, particularly nutritional stress, is one of the major drivers of negative consequences of developmental programming in offspring.…”

Technologies that affect the weaning rate in beef cattle production systems

“…Funston et al (2012a) reported that this feed restriction often prevents cows from presenting adequate body condition score and, consequently, from achieving the required nutritional status for conception. In such cases, feeding strategies using protein supplementation, protein salt, and supplemental Ca salts containing polyunsaturated fatty acids are alternatives to increase body weight and reproductive performance (Lopes et al 2011;Funston et al 2012a;Funston et al 2012b). We found that HWR and IWR farmers offered proteinated salt more frequently than LWR farmers, indicating a better nutrient supply to their herds as shown by the higher weaning rates obtained.…”

Taxa de prenhez em vacas Nelore pós-parto, submetidas ou não a aplicação de eCG 2 dias antes e/ou 14 dias após a IATF

“…Desta forma, os efeitos da utilização da eCG nas taxas de prenhez/ovulação em vacas Nelore têm sido bastante controversos, tendo em vista que a eficácia deste tratamento tem se limitado a vacas com baixo ECC (Baruselli, Reis et al, 2004), não cíclicas (Baruselli, Marques et al, 2001) e vacas primíparas (Small, Colazo et al, 2009). Foi observada uma relação entre o ECC e as taxas de ovulação e prenhez/IA, porém este efeito se deu de forma independente do tratamento com eCG, confirmando a relação entre a condição nutricional e a eficiência reprodutiva (Diskin, Mackey et al, 2003;Funston, Summers et al, 2011). A ausência de interação entre as variáveis ECC e tratamento com eCG contraria alguns estudos que relataram efeito do tratamento com eCG na indução da ovulação em Bos indicus com baixo ECC (2,5), resultando em maior taxa de prenhez (55,4% vs. 40,7%) (Baruselli, Madureira et al, 2004) o que também ocorreu em Bos taurus (Souza, Viechnieski et al, 2009).…”