Effect of Dietary Protein on Prepubertal Mammary Development in Rapidly Growing Dairy Heifers

Whitlock, Brian K; VandeHaar, M.J.; Silva, Luís Felipe Prada e; Tucker, H.A.

doi:10.3168/jds.s0022-0302(02)74221-5

Cited by 30 publications

(32 citation statements)

References 17 publications

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“…Sejrsen et al (1982) reported that heifers raised on high levels of nutrition during the allometric phase of mammary development had less secretory tissue in their mammary glands than those raised at the normal growth rate. Whitlock et al (2002) found that low-protein diets increase the risk of impaired mammary development when heifers are fed for rapid growth and attain puberty early. Silva et al (2002) suggested that fast-growing prepubertal heifers do not have impaired mammary development, and increased body fat may be a better predictor of impaired mammary development than body weight gain.…”

Section: Effects Of High Temperature On Energy Distribution To Proteimentioning

confidence: 98%

Effects of high environmental temperatures on physiological and nutritional status of prepubertal Holstein heifers

et al. 2008

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Section: Effects Of High Temperature On Energy Distribution To Proteimentioning

confidence: 98%

Effects of high environmental temperatures on physiological and nutritional status of prepubertal Holstein heifers

et al. 2008

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“…Whitlock et al [58] [59] assessed the efficiency of MP supply in stimulation of food intake in lactating dairy cows. Two infusions of soya protein isolate (800 g/d) were given either into the rumen-(RP) or the duodenum (DP).…”

Section: Effect Of Mp Supply On Animal Performancesmentioning

confidence: 99%

Metabolizable protein systems in ruminant nutrition: A review

Das¹,

Kundu²,

Kumar³

et al. 2014

Vet World

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Protein available to ruminants is supplied by both microbial and dietary sources. Metabolizable protein (MP) is the true protein which is absorbed by the intestine and supplied by both microbial protein and protein which escapes degradation in the rumen; the protein which is available to the animal for maintenance, growth, fetal growth during gestation, and milk production. Thus, the concept of balancing ruminant rations basing on only dietary crude protein (CP) content seems erroneous. In India, ruminant rations are still balanced for digestible CP and total digestible nutrients for protein and energy requirements, respectively. Traditional feed analysis methods such as proximate analysis and detergent analysis consider feed protein as a single unit and do not take into account of the degradation processes that occur in rumen and passage rates of feed fractions from rumen to intestine. Therefore, the protein requirement of ruminants should include not only the dietary protein source, but also the microbial CP from rumen. The MP systems consider both the factors, thus predict the protein availability more accurately and precisely. This system is aptly designed to represent the extent of protein degradation in the rumen and the synthesis of microbial protein as variable functions. Feed protein fractions, i.e., rumen degradable protein and rumen undegradable protein play vital roles in meeting protein requirements of rumen microbes and host animal, respectively. With the advent of sophisticated nutrition models such as Cornell net carbohydrate and protein system, National Research Council, Agricultural Research Council, Cornell Penn Miner Dairy and Amino Cow; ration formulation has moved from balancing diets from CP to MP, a concept that describes the protein requirements of ruminants at intestinal level, and which is available to animals for useful purposes.

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“…Therefore, the effect that estrogen has on teat length may enable an indirect measurement of mammary epithelial cell development. However, at least one study showed no correlation between teat length and amount of secretory tissue present (Whitlock et al, 2002), potentially negating its usefulness as a noninvasive tool for measuring amount of PAR.…”

Section: Introductionmentioning

confidence: 95%

Examination of weekly mammary parenchymal area by ultrasound, mammary mass, and composition in Holstein heifers reared on 1 of 3 diets from birth to 2 months of age

Esselburn

Hill²,

Bateman³

et al. 2015

Journal of Dairy Science

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Monitoring in vivo growth of mammary parenchyma (PAR) has historically been difficult, necessitating slaughter studies to measure PAR quantity. Advances in ultrasound (US) technology warrant revisiting its use as a noninvasive tool to monitor PAR growth in vivo. The level of nutrient intake during the first 2mo of life may affect measures of mammary growth and composition. Objectives were to examine the utility of US as an in vivo tool to quantify PAR cross-sectional area in Holstein heifers reared on 1 of 3 diets from birth to 2mo of age, assessing potential dietary effects; assess the relationships between weekly US measurements, teat length, manual palpation of PAR scores, and PAR mass at 2mo of age; and examine mammary composition in experimental animals. Holstein heifers (n=24; 41±1kg of initial body weight) from a single farm were randomly assigned to 1 of 3 milk replacers that differed in source and amount of fat. Milk replacer was fed at 660g of dry matter/d until weaning at 42 d. Heifers had ad libitum access to a common calf starter (20% crude protein) and water for the duration of the 56-d trial. Teat length and palpation scores were obtained weekly. A real-time B-mode US with a 7.5-MHz convex probe was used to examine 2-dimensional PAR area in all 4 glands of heifers once weekly from 2 to 3 d of age to harvest at 56 d. The left front and left rear glands were also examined by US 24h postharvest to validate final US measurements, and then bisected to produce a sagittal plane view of PAR for comparison with US images. Mass and composition of mammary gland tissue were determined at 8 wk using standard methodology. Over the course of this 8-wk trial, average teat length increased from 11 to 17mm. The PAR area started small (6.6±3.2mm(2) per gland) and increased to 42.1±2.5mm(2) per gland by the end of the trial. As anticipated, based on measurements obtained at slaughter, US measurements were more related to amount of PAR (r=0.74) than either teat length (r=0.34) or palpation scoring (r=0.63). Importantly, US is quantitative, whereas palpation scoring is subjective. Diet did not affect mass or composition of PAR in young heifers; total udder PAR mass averaged 1.40±0.80g. In conclusion, we showed that in heifers younger than 2mo of age, obtaining weekly PAR measurements via ultrasound is an effective quantitative tool for measuring changes in PAR area in vivo. Future studies may incorporate and expand upon the methods developed here to determine what quantitative evaluation of PAR in young heifers can reveal about milk production capacity.

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Effect of Dietary Protein on Prepubertal Mammary Development in Rapidly Growing Dairy Heifers

Cited by 30 publications

References 17 publications

Effects of high environmental temperatures on physiological and nutritional status of prepubertal Holstein heifers

Effects of high environmental temperatures on physiological and nutritional status of prepubertal Holstein heifers

Metabolizable protein systems in ruminant nutrition: A review

Examination of weekly mammary parenchymal area by ultrasound, mammary mass, and composition in Holstein heifers reared on 1 of 3 diets from birth to 2 months of age

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