Reducing dietary crude protein: effects on digestibility, N balance, and blood metabolites in late-lactation Holstein cows

Our objectives were to determine the effects of reducing dietary crude protein (CP) concentration on nutrient digestibility, rumen function, N balance, and serum AA concentration for dairy cows in late lactation. At the initiation of the experimental period, we stratified Holstein cows (n = 128; mean ± standard deviation 224 ± 54 d in milk) by parity and days pregnant (86 ± 25 d) and assigned them to 1 of 16 pens. For 3 wk, all cows received a covariate diet containing 16.9% CP [dry matter (DM) basis]. For the subsequent 12 wk, we assigned pens to 1 of 4 treatments containing 16.2, 14.4, 13.4, or 11.9% CP (DM basis) in a randomized complete block design. Diets were fed as a total mixed ration once daily. To reduce dietary CP, we replaced soybean meal with soybean hulls in the concentrate mix (DM basis). Diet evaluations suggested that several EAA, especially His, limited productivity as dietary CP declined. Digestibility of DM and CP decreased linearly with dietary CP reduction. Digestibility of neutral detergent fiber and potentially digestible neutral detergent fiber tended to respond in a quadratic pattern with the greatest digestibility at intermediate treatments. The reduction in dietary CP did not affect ruminal pH, but ruminal ammonia-N and branched-chain VFA concentrations declined linearly. The concentration of milk urea-N and plasma urea-N, secretion of milk N, and excretions of fecal N, urinary N, urinary urea-N, and unaccounted N decreased linearly with the reduction in dietary CP concentration. Urinary N expressed as a percentage of N intake was unaffected by dietary CP. Serum concentrations of total essential AA and non-essential AA were unaffected by dietary CP concentration. However, the ratio of essential to non-essential AA decreased with decreasing dietary CP. Serum 3-methylhistidine concentration increased linearly with decreasing dietary CP concentration, indicating greater skeletal muscle breakdown. Although our trial confirmed that reducing dietary CP decreased absolute excretion of urinary N, diet evaluations suggested that milk protein production decreased as certain essential AA became increasingly limited. Thus, reduced-CP diets have the potential to lessen reactive-N outputs of late lactation cows, but more research is needed to design diets that minimize deleterious effects on productivity.

Lissodendoryx Topsent, 1892 (Poecilosclerida: Coelosphaeridae) from Brazil: a new species and transfer of Strongylacidon oxychaetum Menegola, Santos, Moraes & Muricy, 2012 to the genus Lissodendoryx

The genus Lissodendoryx Topsent, 1892 has 118 valid species for the world, with five species records for Brazil. Here, we provide a description of Lissodendoryx (Waldoschmittia) almeidai sp. nov., distinguished from the other species of the subgenus by its spicular dimensions and spicular set, composed of oxeas as choanosomal megascleres, tylotes and arcuate isochelae. Also, we transfer Strongylacidon oxychaetum to Lissodendoryx (Anomodoryx), and record, for the first time, Lissodendoryx (Lissodendoryx) carolinensis from Brazil in addition to Lissodendoryx (Anomodoryx) vulcanus from Pernambuco State.

[A model of primary prevention of sexually transmitted diseases and HIV/AIDS in adolescents]

OBJECTIVE

To develop, apply, and evaluate an educational model for the primary prevention of sexually transmitted diseases (STDs) and acquired immunodeficiency syndrome (AIDS) that was based on the sexual knowledge, attitudes, and practices (KAPs) of adolescents and on their perceptions and behaviors in this area, with the ultimate goal of helping develop educational tools to prevent infection with STDs and the human immunodeficiency virus (HIV).

METHODS

An STD/HIV/AIDS primary prevention model was applied with adolescent schoolchildren (12 to 15 years old) in the canton of Santo Domingo de los Colorados, Ecuador. Two groups with similar characteristics were formed: the experimental group, with 358 students, and the control group, with 288 students. Schools were selected according to inclusion criteria, and adolescents at each school were chosen at random. A discussion guide was applied with 16 focus groups, and the resulting information was used to prepare a KAP survey. After being validated, the KAP survey was applied to the experimental group and to the control group. A prevention education program geared to students and teachers was implemented with the experimental group. Eight months later a second KAP survey was done with the experimental group and the control group. The differences in KAPs before and after the intervention were evaluated using the chi-square test.

RESULTS

There were no statistically significant differences between the two groups before the intervention, but afterwards the differences were statistically significant (P = 0.012), with an increase in the knowledge of sexuality and STDs/AIDS in the experimental group, even though the long-term behavior changes have not been evaluated.

CONCLUSIONS

This study validated a multifactorial STD/AIDS prevention model adapted to the reality of adolescents, and it suggests the possibility of extrapolating this experience more broadly to contexts similar to those of this Ecuador population.

[Early diagnosis of phenylketonuria. Follow up of 2 cases]

A screening program for the early diagnosis of phenylketonuria was initiated 24 months ago in the Servicio de Salud Metropolitano Central. Since then, 2 cases with phenylketonuria have been early diagnosed. These patients started their nutritional treatment, consisting of a phenylalanine restricted diet at 14 and 17 days of age. The children are submitted to periodic medical, anthropometric, neurologic, biochemical and psychometric analysis. With a strict control they maintain phenylalanine plasma levels between 2 and 6 mg%. Both patients have a normal psychomotor development at 4.5 and 6.5 months of age and an anthropometric development at p50 of NCHS.

Dendritic development in the neocortex of adult rats following a maintained prenatal and/or early postnatal life undernutrition

The Golgi-Cox method was used to study the maturation of the large pyramidal cells of the Vth cortical layer in three groups of adult rats: one subjected to undernutrition during the first month of life, another throughout the first 2 mth of life, and the last one during gestation and the suckling period. The main alterations consist of a decrease in the number and span of dendritic basilar processes of large pyramidal cells. In animals malnourished during prenatal life and the suckling period the reduction of the basal dendritic arborization was more apparent. It is postulated that the vulnerable period for the basal dendritic development occupies the period from the end of pregnancy until the first 3 wk of postnatal life in the rat (suckling period). Noxious influences acting during this phase induce sequelae that cannot be reversed by subsequent refeeding. A maintained nutritional insult during prenatal and early postnatal life induces the most severe changes in dendritic arborizations, compared to those resulting from a prolonged postnatal malnutrition.

Dendritic development in the neocortex of adult rats subjected to postnatal malnutrition

The Golgi-Cox method was used to study the maturation of the large pyramidal cells of the Vth cortical layer in two groups of adult rats, one subjected to early postnatal malnutrition and another malnourished only during the second month of life. The main alterations were observed in the pyramidal cells of cortical layer V of rats malnourished during the first month of life. They consist of a decrease in the number and span of dendritic basilar processes. In animals malnourished during the second month of life, the number and span of basilar dendritic processes in pyramidal cells of layer V, were normal. It is postulated that early postnatal malnutrition induced immediately after birth, profoundly disturbs the process of neuronal maturation in the neocortex of the rat brain, probably with permanent effects.