Achieving body weight adjustments for feeding status and pregnant or non-pregnant condition in beef cows

Effect of pregnancy and feeding level on voluntary intake, digestion, and microbial nitrogen synthesis in Zebu beef cows

The objective of this research was to evaluate how pregnancy and feeding regimens affect the feed intake, digestibility, and efficiency of microbial nitrogen (N) synthesis in beef cows. Forty-four multiparous Nellore cows, comprising 32 gestating and 12 non-gestating cows, with an average weight of 451 ± 10 kg, were assigned to either a HIGH (ad libitum) or LOW (limited feeding at 1.2 times maintenance based on the NRC) feeding regimen during the gestational period. The dry matter intake (DMI) in kg/d was significantly greater (P < 0.01) in HIGH-fed cows. The DMI reduced (P < 0.05) in proportion to the shrunk body weight (SBW) as days of pregnancy (DOP) increased. The interaction between feeding level and DOP was significant (P < 0.05) for the digestibility of dry matter (DM), organic matter (OM), N compounds, ether extract (EE), ash- and protein-free neutral detergent fiber (NDFap), gross energy (GE), and total digestible nutrients (TDN). Except for DM and TDN digestibility, there was a reduced nutrient digestibility as gestation progressed in HIGH-fed cows. In contrast, digestibility increased as a function of DOP in LOW-fed cows. Microbial N synthesis (g/day) was significantly higher in HIGH-fed cows (P < 0.001) compared to LOW-fed cows. The efficiency of microbial N production per g of N intake and kg of digestible OM intake was (P = 0.021) and tended (P = 0.051) to be greater in LOW-fed cows compared to HIGH-fed cows. In summary, HIGH-fed Nellore cows reduce feed intake and digestibility with advancing gestation, affecting feed utilization. In addition, LOW-fed cows, showed higher microbial protein synthesis efficiency, potentially making them more nutrient-efficient under challenging nutritional conditions.

Effects of early weaning on the reproductive performance of suckled Nelore cows in the subsequent breeding season

This study aimed to evaluate the effects of early weaning (EW) on body composition, hormone concentrations and metabolites, and reproductive performance of Nelore cows in the subsequent breeding season (BS). Suckled cows that became pregnant by timed-AI (TAI) in the 2020-BS were exposed in 2021 to early weaning at 150 d (27 primiparous [PRI] and 74 multiparous [MUL]) or conventional weaning (CW) at 240 d postpartum (30 PRI and 77 MUL). Body weight (BW) and body condition score (BCS) were determined at 2020-BS, EW, CW, prepartum, and 2021-BS. Blood samples were collected at EW, CW, prepartum (54.75 ± 0.56 d prepartum), and 2021-TAI and assayed for insulin-like growth factor-1 (IGF-I), non-esterified fatty acid (NEFA), and β-hydroxybutyrate (BHB) concentrations. In 2021-BS, cows were exposed to a P4/E2-based protocol for TAI at day 0 (D0), and a second TAI was performed at D22 in females detected with luteolysis (D20) by Doppler ultrasound. The presence of corpus luteum (CL) on D10, estrous expression, and dominant follicle (DF) diameter, and blood perfusion (BP) on D2 and D0 were determined. Data were analyzed by ANOVA or logistic regression of SAS as a 2 × 2 factorial with main factors of parity (PRI or MUL) and weaning strategy (EW or CW). An interaction of parity and weaning strategy was not observed (P > 0.1), but the weight (kg) and BCS were greater (P < 0.05) in MUL cows at the five timepoints, and EW cows were heavier than CW at the moment of CW (541 vs. 493 kg; and 5.3 vs. 4.3), prepartum (551 vs. 506 kg; and 5.2 vs. 4.4) and 2021-BS (475 vs. 450 kg; and 4.5 vs. 3.7). Plasma urea concentration at 2021-BS was greater (P = 0.01) for PRI than for MUL. A parity-by-time interaction was observed (P ≤ 0.05) for concentrations of IGF-I, NEFA, and BHB. PRI cows had greater (P ≤ 0.05) concentrations of IGF-I at EW and greater (P ≤ 0.05) prepartum concentrations of NEFA and BHB than MUL cows. The proportion of cows with CL at D10 was not affected (P > 0.1) by weaning but was greater (P < 0.05) in MUL than in PRI cows (40.4 vs. 15.7%). The diameter of DF and proportion of BP on D0 were greater (P < 0.05) in EW cows than in CW cows. The pregnancy rate (P/AI, %) at the first TAI was greater (P < 0.05) in EW cows (60% vs. 45%), whereas no difference (P > 0.1) was observed at the second TAI. Cumulative P/AI (first and second TAIs) was greater (P < 0.05) in EW cows (81% vs. 63%). In conclusion, weaning at 150 d in Nelore cattle is a strategy to successfully recover the parous cow's body condition and to improve pregnancy success in the next BS, regardless of the cow's parity order.

Short-term liveweight changes of dairy cows measured by stationary and walk-over weighing scales

Monitoring and detecting individual cows' liveweight (LW) and liveweight change (LWC) are important for estimation of nutritional requirements and health management, and could be useful to measure short-term feed intake, water consumption, defecation, and urination. Walk-over weighing (WOW) systems can facilitate measurements of LW for these purposes, providing automated LW recorded at different times of the day. We conducted a field study to (1) quantify the contribution of feed and water intake, as well as urine and feces excretions, to short-term LWC and (2) determine the feasibility of stationary and WOW scales to detect subtle changes in LW as a result of feed and water intake, urination, and defecation. In this experiment, 10 cows walked through a WOW system and then stood individually on a stationary scale collecting weights at 10 and 3.3 Hz, respectively. Cows were offered 4 kg of feed and 10 kg of water on the stationary scale. For each animal, LW before and after eating and drinking was then calculated using different approaches. Liveweight change was calculated as the difference between the initial and final LW before and after eating and drinking for each statistical measure. The weights of feed intake, water consumption, urination, and defecation were measured and used as predictors of LWC. Urine and feces were collected from individual cows while the cow was on the scale, using a container, and weighed separately. The agreement between LWC measured using either stationary or WOW scales was assessed to determine the sensitivity of the scales to detect subtle changes in LW using the coefficient of determination (R²), Lin's concordance correlation coefficient (CCC), and mean bias. The prediction model showed that most of the regression coefficients were not significantly different from +1.0 for feed and water, or -1.0 for urine and feces. The R² and CCC values demonstrated a satisfactory agreement between calculated and stationary LWC and values ranged from 0.60 to 0.92 and 0.71 to 0.94, respectively. A moderate agreement was achieved between calculated and automated LWC with R² and Lin's CCC values of 0.45 to 0.63 and 0.60 to 0.74, respectively. Therefore, results demonstrated that new algorithms and data processing methods need to be continuously explored and improved to obtain accurate measurements of LW to measure changes in LW, especially from WOW scales.

Effects of protein supplementation on Nellore cows’ reproductive performance, growth, myogenesis, lipogenesis and intestine development of the progeny

Context It is hypothesised that protein supplementation in pregnant Nellore cows during the dry season would improve reproductive performance in the next breeding season, as well as growth, myogenesis and intramuscular lipogenesis of the progeny until weaning. Aims To evaluate the effect of maternal nutrition on cow reproductive performance, as well as on the growth, myogenesis and lipogenesis of the progeny until weaning. Methods A total of 92 pregnant cows were fed on pasture, and half of the cows were also fed a mineral–protein supplement (36% crude protein) from 124 ± 21 days of pregnancy to calving. Therefore, two treatments were tested: non-supplemented or supplemented cows. Progeny were weighed after birth, 130 days after birth and at weaning. Six newborn calves from each treatment were slaughtered to collect muscle and jejunum samples to analyse histology and gene expression. In addition, Longissimus thoracis muscle biopsies were collected at 11 days after birth and weaning for gene expression analyses. Key results Supplemented cows had greater bodyweight (P = 0.03) and body condition score (P = 0.05) during gestation, and the pregnancy rate in the subsequent breeding season had a tendency (P = 0.10) to be greater. The progeny from supplemented cows had greater bodyweight at birth (P = 0.05). However, no differences (P &gt; 0.05) were found in bodyweight at weaning or in the average daily gain during this period. Non-supplemented calves had greater SLC27A4 (P = 0.04) expression and a tendency for greater expression of SLC5A1 (P = 0.08) in the jejunum. Muscle gene expression data showed that progeny from supplemented cows had greater expression of myogenic (WNT10B), adipogenic (PPARG, ZFP423, CD36) and fibrogenic (TGFβ1) markers at birth and at weaning (P ≤ 0.10). Conclusions In conclusion, protein supplementation of pregnant Nellore cows leads to positive effects for subsequent reproductive performance and for muscle development of their progeny. In addition, the progeny from feed-restricted cows increases prenatal intestinal development for better nutrients absorption under a potentially impaired environmental condition. Implications The use of protein supplementation in pregnant Nellore cows has a positive impact on the production system, increasing productivity in a cow/calf operation.

Impacts of protein supplementation during late gestation of beef cows on maternal skeletal muscle and liver tissues metabolism

Since nutritional requirements are increased at the end of gestation to meet the demands of the pregnant uterus, pregnant beef cows are susceptible to mobilization of body reserves (mainly fat and amino acids (AAs)) and to alter the metabolism of nutrients in the liver and muscle to support such demands. The objective of this study was to evaluate the effect of CP supplementation on maternal nutrient metabolism in the late gestation of beef cows grazing a low-quality pasture. Forty-three pregnant Nellore cows gestating male fetuses (average age = 6 years; average weight = 544 kg) at 193 ± 30 (mean ± SD) days (d) of gestation were divided into eight groups (experimental units, with four to five cows each). Treatments were (1) control (CON, n = 4): pasture-based (PB) diet without CP supplementation and (2) supplemented (SUP, n = 4): PB diet daily supplemented with 2 g/kg of BW of a 43.5% CP supplement. Liver and skeletal muscle biopsies were performed at 265 days of gestation and samples were collected for mRNA expression. On day 280 of gestation, blood samples were collected to assess plasma levels of AA. The CON-fed cows tended to have greater (P = 0.057) total circulating AA than SUP-fed cows. The circulating glycogenic AA was greater (P = 0.035) in CON than in SUP cows. CON cows was greater for histidine (P = 0.015), methionine (P = 0.007) and alanine (P = 0.036) than SUP cows. The CON- and SUP-fed showed no differences for gluconeogenesis, fatty acid transport and signaling axis markers in the liver. The mRNA expression of markers for skeletal muscle synthesis, p7056k (P = 0.060) and GSK3B (P = 0.096), tended to be greater in cows from CON than SUP group. No differences were found for mRNA expression of markers for skeletal muscle degradation. We conclude that CP supplementation to CP-restricted late-pregnant beef cows reduces the maternal tissue mobilization and changes the profile of plasma circulating AA and the mRNA expression of markers for the synthesis of skeletal muscle tissue.

Weight adjustment equation for hair sheep raised in warm conditions

To estimate the nutritional requirements of hair sheep, knowledge about the animal's weight and its relationships with growth performances is essential. A study was carried with the objective to establish the relationships between BW, fasting BW (FBW), empty BW (EBW), average daily gain (ADG) and empty BW gain (EBWG) for hair sheep in growing and finishing phases in Brazilian conditions. Databases were obtained from 32 studies, for a total of 1145 observations; there were 3 sex classes (non-castrated male, castrated male and female) and 2 feeding systems (pasture and feedlot). The most representative breeds in the database were Santa Ines (n = 473), Morada Nova (n = 70) and Brazilian Somali (n = 47). The other animals in the database were crossbreeds (n = 555). The FBW (kg), EBW and EBWG (kg/day) were estimated according to linear regression. A random coefficient model was adopted, considering the study as a random effect and including the possibility of covariance between the slope and the intercept. The coefficients obtained from the linear regression of the FBW against the BW, EBW against the FBW and EBWG against the ADG did not differ between sex class (P > 0.05) and genotype (P > 0.05). The equations generated to estimate FBW from the BW, EBW from the FBW and EBWG from the ADG are as follows: FBW = -0.5470 (±0.2025) + 0.9313(±0.019) × BW, EBW = -1.4944 (±0.3639) + 0.8816 (±0.018) × FBW and EBWG = 0.906 (±0.019) × ADG, respectively. The low mean squared error values found in the cross-validation confirmed the reliability of these equations. Considering a sheep with a BW of 30 kg and a 100 g ADG, the estimated FBW, EBW and EBWG calculated using the generated equations are 27, 22.65 and 0.090 kg, respectively. In conclusion, the generated equations can be used in growing hair sheep. The validation procedure applied to the generated equations showed that its use for hair sheep seems to be appropriate.

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

Objective

Twenty-four pregnant Nellore primiparous grazing cows were used to evaluate the effects of energy-protein supplementation and supplementation frequency during pre (105 d before calving) and postpartum (105 d after calving) on performance and metabolic characteristics.

Methods

Experimental treatments consisted of a control (no supplementation), daily supplementation (1.5 kg/d of concentrate/animal) and infrequent supplementation (4.5 kg of concentrate/animal every three days). During the pre and postpartum periods, concentrations of blood metabolites and animal performance were evaluated. Ureagenesis and energy metabolism markers were evaluated at prepartum period.

Results

Supplementation frequency did not alter (p>0.10) body weight (BW), average daily gain (ADG), and carcass traits during pre and postpartum. The BW (p = 0.079), adjusted BW at day of parturition (p = 0.078), and ADG (p = 0.074) were greater for supplemented cows during the prepartum. The body condition score (BCS; p = 0.251), and carcass traits (p>0.10) were not affected by supplementation during prepartum. On postpartum, supplementation did not affect animal performance and carcass traits (p>0.10). The dry mater intake was not affected (p>0.10) by supplementation and supplementation frequency throughout the experimental period. Daily supplemented animals had greater (p<0.001) glucose levels than animals supplemented every three days. Supplementation and supplementation frequency did not alter (p>0.10) the levels of blood metabolites, neither the abundance of ureagenesis nor energy metabolism markers.

Conclusion

In summary, our data show that the reduction of supplementation frequency does not cause negative impacts on performance and metabolic characteristics of primiparous grazing cows during the prepartum.

Effect of maternal feed restriction in dairy goats at different stages of gestation on skeletal muscle development and energy metabolism of kids at the time of births

The aim was to determine effects of maternal feed restriction in dairy goats at gestational different stages on skeletal muscle development and energy metabolism in kids at birth. Six pregnant goats were fed 50% of total digestible nutrients (TDN) and crude protein (CP) (NRC, 2007) recommendations in the first half of gestation and then fed to 100% of the recommendations in the second half of gestation (treatment R-M). In the other group, eight pregnant goats were fed 100% of TDN and CP in the first half of gestation and 50% of a restricted diet the second half of gestation (treatment M-R). Birth weight, blood glucose concentration, muscle fiber number, and size of kids at birth were not affected by maternal feed restriction. The mRNA and protein abundance of myogenic, adipogenic and fibrogenic markers were not affected (P > 0.05) by maternal diet. With regard to values for variables in kid energy metabolism, mRNA abundance of the glycolic enzyme HKII was less (P = 0.03) in the M-R group. In conclusion, maternal feed restriction in the first or second half of gestation had no affect mRNA abundance on myogenic, adipogenic, and fibrogenic markers nor were there changes in skeletal muscle mesenchymal stem cell population of kids at the time of birth. There, however, may be detrimental effects on energy metabolism by reducing HKII gene expression in skeletal muscle of dairy goat kids at the time of birth.

Energetic-protein supplementation in the last 60 days of gestation improves performance of beef cows grazing tropical pastures

BACKGROUND

Nutrition is one of the most important factors that affect animal performance, and it therefore also impacts on financial results in beef systems. In this way, finding the best strategy for feeding supplements is of paramount importance. Aiming to evaluate the effect of supplement feeding strategies for beef cows in the last third of gestation, two experiments were conducted. In Experiment 1, 35 pregnant Nellore cows were assigned to a completely randomized design with four treatments: control, which received no supplement; supplementation for the last 30 d of gestation (30-d; 3.0 kg/d); supplementation for the last 60 d of gestation (60-d; 1.5 kg/d); or supplementation for the last 90 d of gestation (90-d; 1.0 kg/d). All supplemented treatments received the same total amount of supplement throughout the experiment: 90 kg (20% of crude protein). A second experiment (Experiment 2) was delineated to evaluate the effects of the amounts offered in Experiment 1 on intake and metabolism. Four multiparous pregnant Nellore cows were assigned to a 4 × 4 Latin square design, with periods of 15 d each.

RESULTS

There was a linear effect of the number of days of supplementation on calving body weight (BW; P < 0.05) and a quadratic effect on BW change from parturition to d 31 post-calving (P < 0.05), with cows on the 60-d strategy losing less BW post-calving. No difference was found in offspring birth BW (P > 0.10). A significant linear effect on interval from parturition to conception (P < 0.05) was observed, with the highest calving to conception interval being observed in the 90-d strategy. The level of supplementation did not affect forage intake or neutral detergent fiber digestibility (P > 0.10). Nitrogen excreted through urine tended to increase linearly with the level of supplementation (P < 0.10).

CONCLUSION

Providing 1.5 kg of supplement during the last 60 d of gestation improves cow performance after calving, reducing the magnitude of BW lost, and reduces the number of days from calving to re-conception in the following breeding season compared to the usually recommended period of supplementation of 90 d pre-partum.