Management Strategies for Lamb Production on Pasture-Based Systems in Subtropical Regions: A Review

Risk effects of meteorological factors on human brucellosis in Jilin province, China, 2005-2019

Background

The impact of climate on zoonotic infectious diseases (or can be referred to as climate-sensitive zoonotic diseases) is confirmed. Yet, research on the association between brucellosis and climate is limited. We aim to understand the impact of meteorological factors on the risk of brucellosis, especially in northeastern China.

Methods

Monthly incidence data for brucellosis from 2005 to 2019 in Jilin province was obtained from the China Information System for Disease Control and Prevention (CDC). Monthly meteorological data (average temperature (°C), wind velocity (m/s), relative humidity (%), sunshine hours (h), air pressure (hPa), and rainfall (mm)) in Jilin province, China, from 2005 to 2019 were collected from the China Meteorological Information Center (http://data.cma.cn/). The Spearman's correlation was used to choose among the several meteorological variables. A distributed lag non-linear model (DLNM) was used to estimate the lag and non-linearity effect of meteorological factors on the risk of brucellosis.

Results

A total of 24,921 cases of human brucellosis were reported in Jilin province from 2005 to 2019, with the peak epidemic period from April to June. Low temperature and low sunshine hours were protective factors for the brucellosis, where the minimum RR values were 0.50 (95 % CI = 0.31-0.82) for -13.7 °C with 1 month lag and 0.61 (95 % CI = 0.41-0.91) for 110.5h with 2 months lag, respectively. High temperature, high sunshine hours, and low wind velocity were risk factors for brucellosis. The maximum RR values were 2.91 (95 % CI = 1.43-5.92, lag = 1, 25.7 °C), 1.85 (95 % CI = 1.23-2.80, lag = 2, 332.6h), and 1.68 (95 % CI = 1.25-2.26, lag = 2, 1.4 m/s). The trends in the impact of extreme temperature and extreme sunshine hours on the transmission of brucellosis were generally consistent.

Conclusion

High temperature, high sunshine hours, and low wind velocity are more conducive to the transmission of brucellosis with an obvious lag effect. The results will deepen the understanding of the relationship between climate and brucellosis and provide a reference for formulating relevant public health policies.

The comparative effect of creep and conventional feeding methods on growth performance and oxidative stress markers in Akkaraman lambs

This study aimed to determine the effect of conventional and creep-feeding methods on growth performance and oxidative stress in Akkaraman (AKK) lambs. For this purpose, the AKK lambs (n = 60) used in this study were divided into four groups (15 n × 2 sex × 2 feeding methods), and all of them were fed the same ration. In the conventional feeding method, the lambs were taken to their dams for suckling twice a day and then kept in a separate compartment for further feeding. In contrast, in the creep-feeding method, the lambs always stayed with their mothers and had free access to supplementary feed by passing through the creep-feeding area. The data for body weights, body measurements, and saliva samples were collected five times, 14 days apart, to evaluate lambs' growth performance and oxidative stress markers. The results showed a higher (P < 0.05) body weight gain in the creep-fed group than in the conventional-fed group. The difference between creep and conventional feeding was significant (P = 0.033), but the difference between the groups in terms of gender was nonsignificant (P = 0.438). The males fed with the creep-feeding (CR-M) group had the largest body length (BL), pectoral chest width (PCW), chest depth (CD), chest circumference (CC), head length (HL), and head width (HW) measurements. The males fed with the conventional feeding (CO-M) group had the largest wither height (WH) measurement, and females fed with the conventional feeding (CO-F) group had the largest back length (BAL) body size. When the overall improvement in body measurements was considered, it was determined that the body sizes of many males in creep-feeding increased more than those of other feeding groups. The oxidative stress marker malondialdehyde (MDA) was higher (P < 0.001) in the conventional feeding group. Other oxidative stress markers, superoxide dismutase (SOD), catalase (CAT), and glutathione s-transferase (GSH-ST), were higher in the creep-feeding group (P < 0.001). Considering these findings, it is possible to conclude that creep-feeding is superior to conventional feeding to get a higher growth rate and reduce oxidative stress in AKK lambs.

Technologies used in ruminant grazing management: an integrative review

The objective of this study was to identify the main technologies used in the management of ruminant grazing. We developed a review protocol in which the search terms were previously tested and based on the PVO strategy to determine the guiding question (population [P]: domestic ruminants; variables [V] of interest: grazing management technologies; and outcomes [O]: intake, performance, and productivity of animals raised exclusively on pasture). The guiding question was the following: What technologies are used in the grazing management of domestic ruminants on pasture? The databases used were SCOPUS (Elsevier), SciELO Citation Index, Science Direct, and Wiley Online Library, and the search was carried out until October 15, 2021. The search identified 2683 research articles; however, only 43 were considered eligible and included due to their methodological robustness for data extraction. The most commonly used species were Lolium multiflorum and Lolium perenne (20%), Panicum maximum (18%), and Brachiaria brizantha (14%). The most widely used grazing methods were continuous grazing (53.4%) and intermittent grazing (39.5%). Among the technologies, the most widely adopted were pasture height (55.8%) and herbage allowance (11.6%). The most frequent sampling methods were the use of a ruler (37.2%) and measuring stick (13.9%) to measure the height, and clipping with a frame (18.6%) to measure herbage allowance. The animals used in the included studies were cattle (n = 1335), sheep (n = 839), and goats (n = 41). Pasture height and herbage allowance were the most widely used grazing management technologies, with the data concentrated mainly in Brazil, in studies with continuous grazing by cattle.

Weaning and concentrate supplementation on the characteristics of carcass cuts and longissimus muscle of Suffolk lambs finished on pasture

The aim of this study was to evaluate the influence of weaning and concentrate supplementation on the characteristics of carcass cuts and longissimus muscle of Suffolk lambs finished on a Tifton 85 (Cynodon spp.) pasture. Weaning and concentrate supplementation strategies were evaluated in four finishing systems: i) non-weaned and non-supplemented lambs; ii) non-weaned lambs supplemented with concentrate in creep feeding; iii) weaned and non-supplemented lambs; and iv) weaned lambs supplemented with concentrate. In the systems with weaning, lambs were weaned at 46 ± 6 days of age. In the systems with supplementation, the concentrate was offered daily at 2% of lambs’ body weight. Weaning led to a decrease, whereas supplementation led to an increase in carcass cut weights. Supplemented lambs had lower yields of neck and uncovered ribs, and higher yields of breast + flank and loin. The characteristics of loin eye and fat thickness over the longissimus muscle presented lower values in weaned lambs and higher values in supplemented lambs. Keeping lambs with their dams and offering concentrate supplementation until slaughter are strategies recommended to obtain heavier cuts with increased muscularity and fat content.

Tropical grass and legume pastures may alter lamb meat physical and chemical characteristics

The present study assessed the influence of the type of the tropical pastures on lamb body weight (BW) gain and meat quality. Fifty-four lambs were allocated to three grazing pastures: (1) AG - Aruana grass (Panicum maximum cv. IZ-5); (2) PP - pigeon pea legume (Cajanus cajan cv. Anão); and (3) CS - contiguous swards, half of the paddock with AG and half with PP. After 92 days of grazing, the lambs were slaughtered. Carcasses were evaluated and the longissimus muscle was collected to determine color, lipid profile, tocopherol concentrations, and lipid oxidation. Although the pastures present differences in the characteristics of nutritional quality, the animals did not show difference in BW gain. The results show that all forage presented similar concentration of alpha-tocopherol (137 ± 14.37 mg kg^-1 of fresh matter), whereas total and condensed tannin contents were greater in PP, intermediate in CS, and the lowest in AG treatment (P = 0.0001). Meat α-tocopherol content was similar among treatments (P = 0.1392), with an average concentration close to the optimal level to reduce the meat oxidation. Meat from AG treatment had 45 and 25% lower n-6/n-3 ratio than meat from PP and CS treatments, respectively. The legume increases the unsaturated fatty acids and the grass can reduce the n6/n3 ratio. The level of condensed tannin concentration did show to have important effect on meat characteristics. Both tropical pastures studied can provide a high amount of alpha-tocopherol, generating a great potential to increase the concentration of this antioxidant in lamb's meat.

The effects of protein supplementation and pasture maintenance on the growth, parasite burden, and economic return of pasture-raised lambs

The objective of this experiment was to evaluate the impact of protein supplementation and pasture contamination with gastrointestinal nematodes on the mitigation of parasitic infection in grazing lambs. We hypothesized that there would be no difference between protein supplementation and newly sown pasture in evaluating lamb growth and health parameters associated with parasitism. Furthermore, we questioned if there would be an interaction between protein supplementation and pasture type. A total of 192, 60-d-old lambs (28.3 ± 5.1 kg) were randomly assigned to one of four treatments: 1) new pasture without supplementation (NN); 2) new pasture with supplementation (NS); 3) established pasture without supplementation (EN); and 4) established pasture with supplementation (ES) and grazed for 112 d. Lambs were supplemented at a rate of 1% body weight/d. Supplemented lambs had greater body weight (BW) and average daily gain (ADG) when compared with non-supplemented lambs (P < 0.04). Additionally, lambs on newly sown pasture demonstrated greater BW and ADG when compared with lambs grazing on established pasture (P < 0.05). For lamb health, lambs in the EN treatment group had the greatest FAMACHA eye scores and lowest packed cell volume (PCV) over the course of the 112-d grazing period (P < 0.05). Moreover, NS and ES treatment lambs demonstrated similar FAMACHA eye scores when compared with NN treatment lambs; however, NN treatment lambs showed lower PCV when compared with NS and ES treatment lambs (P < 0.05). In evaluating fecal egg counts (FEC), lambs on new pasture or given supplement demonstrated lesser FEC when compared with those lambs on established pasture or not given supplement (P < 0.05). Sixty-four lambs were harvested to evaluate total abomasum nematode counts which demonstrated that Haemonchus contortus represented approximately 80% of total nematodes. Furthermore, based upon gross margin analysis, lambs given a protein rich supplement on pasture had a 9.3 kg increase in lamb BW whereas newly sown pasture had a 1.3 kg increase in lamb BW. A protein rich supplement given to lambs grazing pastures contaminated primarily with H. contortus or placing lambs on newly sown pasture increases lamb BW and improves parasite resiliency. Selection of parasite management strategies may be influenced by cost of production and market opportunities.

Influence of tropical upright pasture structural and chemical characteristics on lamb grazing time

Tropical pasture canopy characteristics can alter lamb ingestive behavior. Our study evaluated the ingestive behavior of young lambs in different tropical pastures to identify which variables interfere in their grazing activity. Two years of study were carried out with 54 weaned lambs distributed in three different pasture canopies: 1) monoculture of an upright grass, guinea grass (Panicum maximum; GG); 2) monoculture of a shrubby legume pigeon pea (Cajanus cajan; PP) and 3) contiguous paddock with half GG and half PP (GP). The experiment was set out in a randomized complete block design (3 blocks). Lamb ingestive behavior was observed from sunrise to sunset with records every 5 minutes. To identify the main variables that affected lamb grazing activity, a multivariate analysis of the Decision Tree was performed. Our results showed that there was no difference in the ingestive behavior parameters of young lambs in different canopies (P > 0.05). There was interaction among the canopies and the experimental periods for the variables idleness time and biting rate (P ≤ 0.05). Lambs in all canopies showed more idleness time in the first evaluation period. Lambs in canopies containing grass (GG and GP) exhibited greater bites per minute throughout the experimental period. Lamb grazing time increased 40% as experimental period progressed and plants matured. The Decision Tree identified leaf:stem ratio as the variable that most influenced lamb grazing time in GG and GP canopies while in the PP, grazing time was directly related to canopy height. The behavior of young lambs on tropical pasture is variable as there is a change in the behavioral response to canopy characteristics over time. In addition, the grazing time of these animals can be estimated by means of variables related to canopy structural characteristics (leaf:stem ratio and height) together with chemical variables.