Effects of energy-protein supplementation frequency on performance of primiparous grazing beef cows during pre and postpartum

Effect of Supplementation Plans and Frequency on Performance and Metabolic Responses of Grazing Pregnant Beef Heifers

Our objective was to evaluate the effects of protein supplementation frequency and supplementation plans during gestation on productive performance and metabolic responses of grazing super-precocious Nellore heifers. Thirty-five pregnant Nellore heifers were used in a completely randomized design in a 2 × 2 factorial arrangement with an additional control group. The factors were the following: 1. Frequency of supplementation: (a) Daily (seven times per week), (b) Infrequent (three times per week); 2. Supplementation plans: (a) Constant, (b) Increasing. A control group with no supplementation was included. Two digestibility trials were carried out on the 40th and 130th experimental days. Productive performance and body composition were evaluated in the prepartum and postpartum periods. Blood samples were collected at -114, -113, -15, -14, +15, +30, and +45 days relative to calving for measuring metabolic status. Supplementation (daily and infrequent) increased the intake of total dry matter (DM) (p ≤ 0.004), average daily gain (p < 0.001), and body weight at calving (p = 0.008) at prepartum. However, frequency or supplementation plan did not alter (p > 0.17) the intake of total DM and forage DM. There was an effect (p ≤ 0.02) of the supplementation plan on subcutaneous thickness fat in the prepartum period and albumin and non-esterified fatty acid concentrations (p < 0.004) in the postpartum period. Nonetheless, frequency and supplementation plans did not affect (p ≥ 0.10) heifers' productive performance during the postpartum period. In conclusion, protein supplementation frequency and supplementation plan during beef heifers' gestation do not negatively impact their productive performance or metabolic responses.

Protein supplementation during mid-gestation affects maternal voluntary feed intake, performance, digestibility, and uterine blood flow of beef cows

This study aimed to assess the impact of protein supplementation and its interaction with calf sex (CS) on the performance, metabolism and physiology of pregnant beef cows. Fifty-two multiparous Zebu beef cows carrying female (n = 22) and male (n = 30) fetuses were used. Cows were individually housed from day 100 to 200 of gestation and randomly assigned to restricted (RES, n = 26) or supplemented (SUP, n = 26) groups. The RES cows were ad libitum fed a basal diet (corn silage + sugarcane bagasse + mineral mixture), achieving 5.5% crude protein (CP), while SUP cows received the same basal diet plus a protein supplement (40% CP, at 3.5 g/kg of body weight). All cows were fed the same diet during late gestation. Differences were declared at p < 0.05. No significant interaction between maternal nutrition and calf sex was found for maternal outcomes (p ≥ 0.34). The SUP treatment increased the total dry matter (DM) intake (p ≤ 0.01) by 32% and 19% at mid- and late-gestation respectively. The total tract digestibility of all diet components was improved by SUP treatment at day 200 of gestation (p ≤ 0.02), as well as the ruminal microbial CP production (p ≤ 0.01). The SUP treatment increased (p ≤ 0.03) the cows' body score condition, ribeye area, the average daily gain (ADG) of pregnant components (PREG; i.e., weight accretion of cows caused by pregnancy) and the ADG of maternal tissues (i.e., weight accretion discounting the gain related to gestation) in the mid-gestation. The SUP cows exhibited a lower maternal ADG (p < 0.01) compared to RES cows in late pregnancy. There was a 24% additional gain (p < 0.01) in the PREG components for SUP cows during late gestation, which in turn improved the calf birthweight (p = 0.05). The uterine arterial resistance and pulsatility indexes (p ≤ 0.01) at mid-gestation were greater for RES cows. In conclusion, protein supplementation during mid-gestation is an effective practice for improving maternal performance, growth of the gravid uterus and the offspring's birth weight.

Expression of enzymes involved in the urea cycle and muscle and mammary gland development of Holstein × Gyr heifers in a rotational grazing system supplemented with increasing protein levels

Studies evaluating the crude protein (CP) supplementation strategies across the year for grazing cattle and its association with the enzymes involved in the urea cycle and muscle and mammary gland developments are scarce. Thus, we aimed to evaluate the effect of supplementation with different levels of CP on the expression of genes involved in the urea cycle and muscle and mammary gland development of Holstein × Gyr crossbreed heifers grazing intensively managed Brachiaria decumbens throughout the year. Thirty-eight heifers with average initial BW of 172.5 ± 11.15 kg (mean ± SE) and 8.2 ± 0.54 mo of age were randomly assigned to 1 of 4 treatments: 3 protein supplements (SUP) fed at 5g/kg of body weight, plus a control group (CON, non-supplemented animals). The supplement CP levels evaluated were: 12, 24, and 36%. The study was divided into 4 seasons: rainy, dry, rainy-dry transition (RDT), and dry-rainy transition (DRT). On the penultimate day of each season, ultrasound images of the carcass and mammary gland were taken. Five animals from each treatment were randomly chosen on the last day of each season, and liver and muscle tissue biopsies were performed. The target genes were the mammalian target of rapamycin (mTOR) and adenosine monophosphate-activated protein kinase (AMPK) in the muscle samples. Carbamoyl phosphate synthetase (CPS), ornithine transcarbamylase (OTC), argininosuccinate synthetase (ASS), arginosuccinate lyase (ASL), and arginase (ARG) were evaluated in the liver samples. Data were analyzed using PROC GLIMMIX of the SAS with repeated measures. We observed a greater rib eye area (cm2) and fat thickness (mm) in SUP animals than in non-supplemented animals. However, we did not observe differences among SUP levels for both variables. No effects of supplementation were detected on mammary gland development. Nevertheless, seasonal effects were observed, where the RDT and dry season had the most and least accumulated fat in the mammary gland. In muscle, we observed greater expression of AMPK in non-supplemented animals than SUP animals. On the other hand, no differences were observed in gene expression between SUP and non-supplemented animals and among SUP animals for mTOR. Season affected both AMPK and mTOR; heifers had a greater AMPK gene expression on rainy than RDT. For mTOR, we observed greater gene expression in RDT and DRT than in rainy. No differences were observed among RDT, dry, and DRT, and between dry and rainy seasons for mTOR. We observed greater CPS, ASL, and ARG gene expression in SUP animals than in non-supplemented animals. Among SUP animals, supplement CP linearly affected CPS. In conclusion, the supplementation strategy did not affect mammary gland development and mTOR expression in muscle tissue. However, we observed a seasonal effect on mammary gland development and AMPK and mTOR expression. The CP supplementation increased the rib eye area and fat thickness, directly affecting AMPK expression in the muscle. Moreover, the CP supplementation increased urea cycle enzyme expression, indicating greater urea production in the liver.

Evaluation of Maternal Nutrition Effects in the Lifelong Performance of Male Beef Cattle Offspring

This study aimed to evaluate the effects of different prenatal nutrition treatments on pregnant cows and their progeny. One hundred and twenty-six pregnant Nellore cows (455.3 ± 8.1 kg) were allocated in three different nutritional treatments during pregnancy: NP-control, PP-protein-energy supplementation in the last 3 months of pregnancy, and FP-the same supplementation throughout pregnancy. After parturition, all cows and calves received the same environmental and nutrition condition. The body condition score (BCS), body weight (BW), ribeye area (REA), backfat thickness (BFT), and rumpfat thickness (RFT) were collected on four occasions during pregnancy in the cows and from birth to finishing in calves. All data (cows and calves) were submitted to an analysis of variance (p < 0.05) using a linear model (MIXED procedure; SAS software). The BW, RFT, and BCS from the cows showed significant differences in the middle third of pregnancy and pre-delivery and RFT postpartum (p < 0.05). For the offspring, the weaning weight showed a tendency (NP lighter than others). In terms of gain, the PP group tended to be higher in RFT at calving (p = 0.06), in REA at finishing (p = 0.09), and in ADG in the same period (p = 0.09). The prenatal nutrition strategies had little or no effect on the beef cattle postnatal performance.

The Effects of Prenatal Diet on Calf Performance and Perspectives for Fetal Programming Studies: A Meta-Analytical Investigation

This meta-analysis aimed to identify knowledge gaps in the scientific literature on future fetal-programming studies and to investigate the factors that determine the performance of beef cows and their offspring. A dataset composed of 35 publications was used. The prenatal diet, body weight (BW), average daily gain (ADG) during pregnancy, and calf sex were elicited as possible modulators of the beef cows and their offspring performance. Then, the correlations between these variables and the outcomes of interest were investigated. A mixed multiple linear regression procedure was used to evaluate the relationships between the responses and all the possible explanatory variables. A knowledge gap was observed in studies focused on zebu animals, with respect to the offspring sex and the consequences of prenatal nutrition in early pregnancy. The absence of studies considering the possible effects promoted by the interactions between the different stressors' sources during pregnancy was also detected. A regression analysis showed that prenatal diets with higher levels of protein improved the ADG of pregnant beef cows and that heavier cows give birth to heavier calves. Variations in the BW at weaning were related to the BW at birth and calf sex. Therefore, this research reinforces the importance of monitoring the prenatal nutrition of beef cows.

Effects of replacing ground corn with Nopalea cochenillifera meal on the intake, performance, and economic viability of grazing steers

The objective of this study was to evaluate the effects of replacing different levels of spineless-cactus meal instead of ground corn on supplements for crossbred steers grazing in Urochloa brizantha cv. Marandú pastures. Forty crossbred steers with an average body weight (BW) of 261 ± 7.46 kg were distributed in a completely randomized design. In supplements, the ground corn grain was substituted with 0%, 30%, 60%, and 90% spineless-cactus meal. The substitution of spineless-cactus meal instead ground corn promoted a linear decrease in the ether extract (EE; P = 0.03) and non-fibrous carbohydrates (NFC; P < 0.01) intakes. The apparent digestibility of EE was influenced (P < 0.05) showing a linear decrease. The apparent digestibility of NFC had a quadratic effect (P = 0.03). For the neutral detergent fiber corrected for ash and protein, the apparent digestibility increased linearly (P = 0.01). The average daily gain showed a quadratic effect (P < 0.01), with a maximum response estimated at 44.94% (1055.52 g/day) substitution with spineless-cactus meal for ground corn. The cost per animal per period and the cost per hectare decreased linearly (P < 0.01). The revenue, net revenue, exchange rate, and monthly revenue of the activity showed quadratic responses to the spineless-cactus meal supplements (P < 0.01), with maximum effects at 44.99%, 47.46%, 61.25%, and 57.35%, respectively. The substitution with up to 44.94% of spineless-cactus meal for ground corn provided daily gains, increased the feed conversion, and was favorable as a cost to the production system. Moreover, the profitability increased with maximum animal performance and improved use of fiber from pastures.

Provision of a protein-rich supplement for grazing suckling female beef calves to improve productive performance and metabolic response

Objective

This study was conducted to evaluate the effects of the provision of a protein-rich supplement on productive performance, and metabolic profile on grazing suckling female beef calves in tropical conditions during 150 d of experimentation.

Methods

Fifty-six Nellore suckling female calves, and their respective dams were distributed in a completely randomised design and made to undergo two treatments as follows: UNS (without supplementation), and SUP (supplementation with 5 g/kg body weight [BW] of a protein supplement). Throughout the experiment, animal performance and metabolic profile were evaluated. Also, ureagenesis and gluconeogenesis were assessed for gene expression.

Results

SUP female calves showed a higher voluntary intake (p≤0.03) of the diet components evaluated, digestibility of organic matter (p≤0.02) and microbial nitrogen production (MICN; p≤0.02) compared to UNS female calves. In its turn, serum urea nitrogen (p≤0.01) and insulin-like growth factor-1 (p≤0.03) levels and ureagenesis (p≤0.04) increased in SUP female calves compared to UNS female calves. Blood glucose and triglyceride levels were not affected by supplementation. The average daily gain (ADG) from SUP female calves was higher (p≤0.02) compared with UNS female calves. However, supplementation did not affect the body measures of the animals.

Conclusion

In summary, provision of a protein-rich supplement improves the intake and nutrients digestibility, ADG and final BW and increases metabolic indicators of the protein status in grazing suckling female beef calves in tropical conditions.