RESUMO

Creep feeding has been used to reduce calves' nutritional dependence on the cow, but research results under tropical conditions have not been conclusive about the effects on the cow. Therefore, this study was conducted to evaluate the effects of high and low supplementation levels for Nellore heifer calves on performance, milk production, and metabolic profile of their mothers. Fifty multiparous Nellore cows and their respective calves were used. The following treatments were evaluated: 0-control, no supplement was fed to calves; 3-calves received supplement in the amount of 3 g/kg of body weight (BW); 6-calves received supplement in the amount of 6 g/kg of BW. There was no significant effect of level of supplementation offered to offspring on cow BW, body condition score (BCS) and subcutaneous fat thickness (P > 0.05). Level of supplementation of heifer calves did not significantly affect milk production corrected to 4% of fat (P > 0.05). Fat, protein, lactose, and total solids of the milk also did not differ among supplementation strategies (P > 0.05). Level of supplement fed to calves had no effect on cows' glucose, total cholesterol, HDL, LDL, triglycerides, total protein, and albumin levels (P > 0.05), but cows nursing calves that did not receive supplement had lower level of serum urea N (SUN; P < 0.05). We conclude that creep feeding in the amounts of 3 or 6 g/kg of BW daily has no major impact on dams' performance and metabolism.

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RESUMO

O trabalho visa analisar as características histológicas da placenta bovina, Bos taurus indicus criados na região Oriental da Amazônia. Foram coletados úteros gravídicos entre 4 a 8 meses de gestação. Realizou-se secção dorsal ao longo da cérvix até o corpo do útero. A peça foi invertida para verificação da idade fetal e coleta dos placentônios. Foram coletados placentônios, do corno uterino gestante e não gestante com forma oval, circular e em fusão. Em seguida as peças foram fixadas em solução de formol a 10%, para posterior preparação histológica em parafina e coloração em hematoxilina-eosina. Os placentônios apresentavam um estroma endometrial bem desenvolvido e vascularizado revestindo a carúncula e apresentando lacunas, os cotilédones possuíam vilosidades revestidas por células trofoblásticas uninucleadas e binucleadas. O epitélio da mucosa era do tipo prismático simples e as glândulas do cório próximas ao limite do miométrio possuíam aspecto tortuoso. Carúncula e cotilédone estavam revestidos respectivamente por epitélio cúbico simples e células trofoblásticas em meio à lacunas da placenta. A partir dos 6 meses observou-se um estroma fibrovascular compacto. Concluiu-se que a placenta mesmo possuindo diversidade anatômica entre as estruturas encontradas, apresenta características histológicas semelhantes em todos os períodos gestacionais estudados, e o crescimento dos placentônios no decorrer da gestação parece estar relacionado com a multiplicação das células que formam os cotilédones e carúnculas, bem como da vascularização.

The aim of the present work was to analyze the histological characteristics of placenta of zebu, Bos taurus indicus, raised in the Oriental Amazon. Pregnant uteri from 4 to 8 months of gestation were collected. Samples were seccionated from the cérvix to the body of the uterus. Samples were inverted for fetal age verification and to collect the placentomes. Placentomes were collected from pregnant and non-pregnant oval, circular and fusion uterine horns. Then, they were fastened in formalin solution 10% for subsequent histological preparation in paraffin and hematoxilin-eosin for coloration. Histologically, the endometrium was well developed with vascular covering of the caruncle and presenting gaps. The cotyledone had villous covered by trophoblast uninucleated and binucleated giant cells. The mucosal epithelium was simple prismatic and corium glands in the limit of the myometrium presented tortuous appearance. Caruncule and cotyledone were covered respectively by simple cubic epithelium and trophoblast giant binucleate cells. A compact fibrovascular estrome was formed from the 6th month of pregnancy. It was concluded that, even having anatomical differences among found structures, the placenta presents similar histology in all periods studied, and placentomes growth during gestation seems to be related to the multiplication of cells that make up the cotyledons and caruncule, as well as vascularisation.

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