The effect of heifer dietary protein intake during gestation on fetal and postnatal development of their progeny: attention to the circulatory IGF-axis and the autocrine IGF-axis of skeletal muscle and adipose tissue

Gina Micke (2011). The effect of heifer dietary protein intake during gestation on fetal and postnatal development of their progeny: attention to the circulatory IGF-axis and the autocrine IGF-axis of skeletal muscle and adipose tissue PhD Thesis, School of Veterinary Science, The University of Queensland.

       
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Author Gina Micke
Thesis Title The effect of heifer dietary protein intake during gestation on fetal and postnatal development of their progeny: attention to the circulatory IGF-axis and the autocrine IGF-axis of skeletal muscle and adipose tissue
School, Centre or Institute School of Veterinary Science
Institution The University of Queensland
Publication date 2011-03
Thesis type PhD Thesis
Supervisor VEA Perry
ST Norman
Total pages 203
Total black and white pages 203
Subjects 07 Agricultural and Veterinary Sciences
Abstract/Summary The beef producing northern pastoral and southern agricultural zones of Australia share an inherent seasonal pattern of pasture quantity and quality. Protein deficiency is a feature of dry season pastures in the northern pastoral zone, whilst protein oversupply is a feature of improved and legume based pastures in the southern agricultural zone. Maternal nutrient intake during gestation has been linked to perturbations to the postnatal growth pathway, the body composition and the metabolism of their progeny. This thesis investigates the effect of heifer (n = 120) protein intake during the first two trimesters of gestation on fetal (n = 71) growth; dystocia and progeny (n = 68) postnatal growth. It also investigates this effect on the circulatory, skeletal muscle and adipose tissue insulin-like growth factor (IGF) axes of the progeny. The study was based at Goondiwindi, Australia (latitude 28.52S, longitude 150.33E) and consisted of a two-by-two factorial design. On the day of artificial insemination (AI), heifers were allocated by stratification by weight and genotype to one of four treatment groups. Treatment groups were defined by the amount of crude protein (CP) fed to each heifer during the first (AI to 93 days of gestation (gd)) and second (94 to 180 gd) trimesters of gestation (HH: first trimester = 1.4 kg CP/d and 76.3 MJ ME/d, second trimester = 1.4 kg CP/d and 82.4 MJ ME; HL: first trimester = 1.4 kg CP/d and 76.3 MJ ME/d, second trimester = 0.4 kg CP/d and 63.1 MJ ME/d; LH: first trimester = 0.4 kg CP/d and 62.5 MJ ME/d, second trimester = 1.4kg CP/d and 82.4 MJ ME/d; LL: first trimester = 0.4kg CP/d and 62.5 MJ ME/d, second trimester = 0.4 kg CP/d and 63.1 MJ ME/d). All heifers were fed 1.06 kg CP/d and 71.45 MJ ME/d from 181 gd until parturition. Progeny remained with their mothers until weaning at 191 days of age (d). From weaning until 401 d they were managed as a single group grazing native pastures at Goondiwindi. From 401 d they were managed as part of a larger group of yearling cattle at Surat, Queensland (27°16′S, 149°07′E) before commencing an intensive feedlot finishing program at 541 d at Dalby, Queensland (27°18′S, 151°26′E). They were commercially slaughtered at 680 d. Heifers fed low compared to high protein diets during the first trimester of gestation had smaller fetuses at 39 gd and progeny with greater expression of IGF-IR mRNA in their SC adipose tissue at 680 d. There were further sex-specific effects of heifer diet during the first trimester of gestation. Male progeny exposed to maternal diets low in protein during the first trimester of gestation were heavier and leaner during the post-weaning period and had greater cross-sectional areas of their semitendinosus and longissimus dorsi muscles when compared to their high protein exposed counterparts. These changes were accompanied by greater IGF-I and IGF-II mRNA expression in their semitendinosus muscle and lower LEP mRNA expression in their PR adipose tissue at 680 d. In contrast, female progeny exposed to maternal diets low in protein during the first trimester of gestation were lighter and of smaller stature during the post-weaning period which resulted in them having lighter carcasses at 680 d. In addition they had greater expression of IGF-IIR mRNA in their semitendinosus muscle but decreased expression of IGF-I mRNA in PR adipose tissue at 680 d when compared to their high protein exposed counterparts. In comparison, heifers fed low protein diets during the second trimester of gestation had lower birthweight calves, an effect that persisted to 29 d, in addition to having calves with greater plasma NEFA concentration at birth than those that were fed high protein diets during the same period. These progeny went on to have greater cross-sectional area of their longissimus dorsi muscle at slaughter; greater expression of IGF-IR mRNA in their semitendinosus muscle, IGF-II mRNA in PR adipose tissue and LEP mRNA in OM adipose tissue, but lesser expression of IGF-IR, IGF-II and IGF-IIR mRNA in their omental adipose tissue at 680 d when compared to their high protein exposed counterparts. A change to maternal diet from high to low protein, or visa versa, at the end of the first trimester of gestation resulted in a male offspring with greater plasma IGF-I concentrations during the postnatal period compared to their counterparts exposed to a constant plane of nutiriton. Importantly, pelvic area measurements obtained prior to conception remained valid in their assessement of the relationship between pelvic area and the likelihood of dystocia occurring in the event of changing maternal nutrient intake during gestation. Heifer protein intake during gestation has a permanent sex-specific effects on: fetal and postnatal growth; the endocrine IGF-axis of progeny; and the autocrine/paracrine IGF-axes of skeletal muscle and adipose tissue of the progeny. These findings may assist cattle producers to optimise both welfare and financial outcomes for the heifer herd.
Keyword bovine
Adipose Tissue
Dystocia
fetal programming
IGF
Postnatal growth
Prenatal nutrition
Protein
Skeletal Muscle

 
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Created: Thu, 13 Oct 2011, 14:15:16 EST by Miss Gina Micke on behalf of Library - Information Access Service